TRWITION MnAL COMPLEXES OF SCHIFF BASES BY MouLI ALEEL, U.C. Dr. Gcetha Tararncs~val-an I'rofcssor Department of Chemistry University of Calicut Calicut University P.O. Kcrala -. h73 635 This is to certify that the thcsis entitlcd Synthesis, Thern?al ancl Spcctral Studies of some Trn~lsitiolll Mctal Complexes of Schiff Bases is an ~utlicnticr ccord nf the research \vor.k carrid out by Mr. Abdul Jalecl U. C . undcr my supcr\~ision in partial fi~lfillrnento f tlic requirements for thc dcb~eeo f Doctor of Pl~ilosophyi n Che~nistryo f the University of Calicut, and further that no part thcrcoi'hns bcen presented bcforc for any othcr dcgrcc . Dr. Ccctha P P ~ - ~ ~ c s \ \ , R I - ~ I I (Supervisi~igT e~chcr,) C.U. Campus 22"dJ unc 2005 I Iicreby declare that t!lis thesis entitled Synthesis Thern~ala nd Spcctral Studies of some Transition Metal Con~plexeso f Schiff Dascs submitted to the University of Calicui in partial fu!fillmcnt of the requirements for tllc Doctoral Dcgree in Chemistry is (t bonafide rese~rchw ork done by me under the supcrvision and gr~idancco f Dr. CJeetliz Paranjeswaran, Professor. Dcpartnicnt of Chemistry, University of Calicut. I further declare that this thesis has not previously formei! tlie basis of any degree, diploma or other similar titlc. C.U. Campus 22"' Jr~nc 2005 PREFACE Coordination conlpounds have been a great challenge to the clien~istss incc ninetecntll century. Thcir versatility in the diflcrcnt fields of applied science is making much significance. In addition to the different applications in the applied science, structural characteristics are also gaining mucl1 momcntuin. 111 tlic prcsent study. monovalent bidentatc and bivalent tetradentate Schiff basc ligands and tlieir con~plexesa re prepared and characterized on thc basis of elemental analysis. magnetic and conductancc mcasurenients, UV, Visible, IR, NMR and Thermal data. These results arc s ~ i m a r i z c din Part I. "The present study is focused mainly on the metal complexes of Schiff bases derived from dimedone, cyclohexanone and pyrolidone. Scven new ligands viz dimcdone semicarbazone (H2DSC), dimcdonc- bjs -2-aminopl~enol (I42DAP). dimedone bis -2-aminothiopheno1 (ItDATP). cyclo1lcxanonc-2-aminophcnol (HCAP), cyclohexanone-2-aminothiophcnol (E1CATP) pyrolidonc-2-aminophenol (NPAP) and pyrolidone-2-aminotl~iophenol( HPAI'P) and their transition metal chelates hi^\.^ 1)ecn synthesized and characterized. Mn (IT), CO (111, Ni (11). Cu (11)- Z11 (IT) and Cd (11) are the nlctal ions used for complcxntion. Thermo analytical stu(1ics of nine selected Schiff base coniplexes arc carried out using T. G., order of reaction, activation energy, entropy of activation, cnthalpy of actiwtion and free cncrgy of activation are evaluated using the Coats-Redfern equation. Tlie results are interpreted in Part 11. Thermal data further confirms tlie structure o f tlie above complexes. Part 111 consists of investigations on tlie antifungal activity of the ligands and their metal Complexes. A soil born fungus Phylophthora cu;lsici that affects and destroys black pepper is used for this study. Tlie materials and nietliods uscd for the study of antifungal activity are described in this Part 111. A detailed list of references arranged in serial order is given at the end of each part. The research work presented in this thcsis has partly been published /under publication as indicated I 1 Anti fi~ngasl tudies on Cu (11) Schiff base coniplexes .; Abd111J aleel U.C. Dr Suslieela Bhai and Dr Cieetlia Parameswaran in S1c7etleshi Science Corigrcss held at M.S Swaminatlian Research foundatio~2i 003. Meclianism of anti fungal activitics of Scliiff base cotnplcxes with special reference to the mode of iriliibition on elcctron transfer processes in mitocl~ondrialr espiration of P/?vtoph/lrora Cupsici. Abdul Jnlecl U.C. Dr Saju Kanam. Dr Swheela Bhni, Dr Anand Raj and Dr Gectha Parntneswaran ( to be commutiicatcd). Therm0 analytical and pliysico clieniical activity studies of Cu (II).Ni (11). Zn(l1) complexes of dimcdonc -Schiff bases . Abdul Jaleel U.C and Dr Geetha Parameswaran. (communicateci). C.U. Campus 22"'~une 2005 ACKNOWLEDGEMENTS I wish to record niy profound gratitude ancl indebtedness to Dr. Geetha Paramcsmal-an, Professor, Dcpartmcnt of Chemistry. for her able guidance and infinite patience that enabled me to complete this work successhlly. I also chcrish in niy mind the human touch she had given to our collective endeavor through her words of love and appreciation. I rcniember with gratitude Dr Aravindakshan, Head of tlic Department of Chcniistry, University of Calicct for providing rnc tvitli all tlie facilities to do tlie research work. I also thank Mr. Prasad M Alex Research scholar in the Department of Chemistry, University of Calicut for his help and c1icouragcn7cnt. 1 am grcatly indebted to Dr. Y. R. Smma (Former Director IISR), Dr Anand Raj (Prificipal Scientist) and Dr S111iccla bhai (Scicntist), Illdia~iI nstitute of Spices Rescarcli and to Dr. Saju Kanatn Research Associate, Plant Pathology, T.T.S.R. for their ~ i i~ l t i far ioliuel~p in carrying out thc antif~tiigasl tudies at tlicir institute. I am extremely tliankful to Mr. ICripaknran.( N.1.T 'rricliy ), and Jislia (RRL,. Trivandruni) fix :heir timely hclp in gctting the TG , Micro analytical data and NMR spectra. Finally, I would likc to express my t11nr.k~te achers, colleagucs and friends at Dcpt of Chemistry, Calicut University. for their valuzble atggcstions and for all the pains they have taken to forniat the thesis in tlic prcsent ibrni. C.U. Canipr~s 22""une 2005 ABBREVIATIONS For the sake of easiness in description, the following abbreviations are used in this thesis. H2DSC : Dimedone bis semicarbazone HLDATP : Dimedone bis-2-aminothiophenol H2DAP : Dimedone bis-2-aminophenol HCATP : CycIs5exanone-2-aminothiophenol HC AP : Cyclohexanone-2- aminophenol HPATP : Pyrolidone-2- aminothiophenol HPAP : Pyrolidone -2-aminothiophenol M : Central metal atom L : Ligand moiety in a complex CONTENTS PART I SYNTHESIS AND CHARACTERIZATION Page Chapter 1 Introduction 1 Chapter 2 Materials, Methods and Instruments 29 Chapter 3 Studies on Mn (11), CO (11), Ni (11), Cu(II), Zn(I1) and 33 Cd (11) Complexes of dimedone bis semicarbazone (H2DSC) Chapter 4 Studies on Mn (11), CO( 11), Ni (11), Cu (11), Zn (11) and Cd (11) 49 Complexes of H2DATP :dimedone bis-2-aminothiophenol H2DAP : dimedone bis-2-aminophenol Chapter 5 Studies on Mn (11), CO (11), Ni (11), Cu (11), Zn (11) and Cd (11) 64 Complexes of HCATP:cyclohexanone-2-aminothiophenol HCAP cyclohexanone -2-aminophenol Chapter 6 Studies on Mn (11), CO( 11), Ni (11), Cu (11), Zn (11) and Cd (11) 79 Complexes of HPATP: pyrolidone-2- aminothiophenol HPAP : pyrolidone-2- aminophenol References PART I1 THERM0 GRAVIMETRIC ANALYSIS OF SCHIFF BASE COMPLEXES Chapter 1 Introduction 100 Chapter 2 Thermal decomposition kinetics of Ni (11), Cu (11) and 108 Zn (11) complexes of dimedone bis semicarbazone (H2DSC) Chapter 3 Thermal decomposition kinetics of Ni (11), Cu (11) and 112 Zn(I1) complexes of dimedone bis-2-aminothiophenol : H2DATP Chapter 4 Thermal decomposition kinetics of Ni (11), Cu (11) and Zn (11) complexes of dimedone bis-2-aminophenol : H2DAP: References PART I11 ANTIFUNGAL ACTIVITIES OF SCHIFF BASE COMPLEXES Chapter l Introduction Chapter 2 Materials and Methods Chapter 3 Antifungal Activity of the Ligands H2 DAP, H 2DATP, HPAP, HCAP, and their various metal complexes References Summary PART I SYNTHESIS AND CHARACTERIZATION Abdul Jaleel.U.C “Synthesis, thermal and spectral studies of some transition metal complexes of schiff bases” Thesis. Department of Chemistry , University of Calicut, 2005 PART I Synthesis and characterization of Schiff base complexes Introduction and review Introduction One of the most productive areas of chemical research in the modern era is the development of co-ordination chemistry. The limits of coordination chemistry are dificult to define. It may range fkom realm of inorganic, physical and organic chemistry to the edges of theoretical physics and even bioinorganic chemistry .The progress in co-ordination chemistry and complexity and variety of coordination compounds are the main reasons for the renaissance of inorganic chemistry leading to the present period of rapid growth. The new correlations in it gave a fkesh unity to whole of chemistry and the division between inorganic chemistry and organic chemistry was finally broken down. At the very end of 18'~centur~Fr ench chemist Tassaert observed that ammonia combined with a cobalt ore to yield a mahogany colored product which is most likely the first known coordination compound. Throughout first half of nineteenth century other, often beautifully crystalline, examples of various cobalt ammoniates were prepared and in the second half ammoniates of chromium and platinum were prepared. Early milestones in the synthesis of co-ordination compounds are given in the fig 1 Figure 1 Early milestones in the development of Coordination Compounds [C~(NH,S~I~+ Libau 1597 Fe4 [Fe(C N) ,l, Anonymous 1731 CN I ...-C N NCC C 0-, I CN CN Vauquelin 1813 Gmelin 1622 A Zeisse 1827 Pe y rone 1644 Mond 1090 Despite various attempts, however no theoretical basis was developed to satisfactorily account for these wondrous compounds. Although Bolomstrand and Jorgensen offered some explanations for the valence state of these compounds by chain theory , it was Werner theory which gave first scientific explanation for the valence state and stereochemistry of these compounds. Synchronized with the evolution of principles of chemical bonding, theory of coordination chemistry systematically progressed fi-om Werner to the CFT and molecular orbital theory. Later it became possible to amalgamate CFT and MOT, the resulting ligand field theory developed by Lesle Orgel made dramatic contribution to the revival of inorganic chemistry. Coordination compounds brought about a synthetic revolution in inorganic chemistry which led to novel products of equally novel applications in wide range of areas such as analytical chemistry, fungicides, paints, pigments, polymers pharmaceuticals, catalysis and photoconductors. Biomolecules such as hemoglobin, chlorophyll, B complex are the metal chelates, which plays an important role in life sustaining process of nature. Investigating the role and effect of chelation reveals its central role in biological systems and synthetic pathways in inorganic chemistry The term coordination chemistry almost invariably refers to the chemistry of transition metals. Strongly perturbing, partly filled d orbitals make transition metal ion excellent in complex formation. Tendency for coordination, stereochemistry of the complexes and physical and chemical properties differ widely from metal to metal and fi-om oxidation state to oxidation state. Although transition elements have many useful applications and unique properties, it is being understood that complexation modifies their functional properties. Hence investigating formation and characteristics of new complexes have much significance. Schiff bases are typically formed by the condensation of a primary amine and an aldehyde. The resultant functional group, R'HC=N-R", is called an imine and is particularly suitable for binding metal ions via the N atom lone pair, especially when used in combination with one or more donor atoms to form polydentate chelating ligands or macrocycles. Ketones will also form imines of the type R'R"C=N-R"', but the reactions tend to occur less readily than with aldehydes. Examples of a few compounds of interest are given below. Because of the versatility offered by this ligand donor group for the design of interestinglindustrially useful ligand systems, it is motivating to do fbrther research work which aim to develop the coordination chemistry of multidentate chelating Schiff base ligands. Review shows that transition metal complexes of Schiff bases have emerged as highly effective catalyst for various important reactions. Catalysis plays an essential role in synthesizing a diverse group of molecules for the mass production of drugs and other chemical compounds In drug development, often only one of the two mirror images of a compound generally has the desired biological effect, while the other is ineffective, or perhaps even harmful. In order to ensure the safety of a chemical compound, it must be enantiomerically pure. So asymmetric catalysis used for designing a catalyst that is able to selectively control the formation of a desired stereo isomer, where new Schiff bases are playing a central role. Such a penta denate suphonamide ligand is reported by Karno et al. 1. It was envisaged that a pentadentate ligand could coordinate to metals and leave an open coordination site that could bind and activate a substrate in a Lewis acid catalyzed reaction. These ligands are easily synthesized and should readily bind to transition metal complexes to provide chiral Lewis acids for use in asymmetric catalysis. Another report by Genet et al. also accounts for the use of palladium chiral complexes of schiff bases in the sterioselective synthesis of alpha amino acids. Benzophenone irnine of glycine methyl ester palladium complex acted as prochiral nucleophile in the allylic alkylation. Good chemical yield were obtained. Catalysis can be performed at low temperature. Study of Debabrata chatterji is an example for selective catalytic activity. Tridentate Schiff base complexes of ruthenium (111) is used in the 0x0 transfer from tert ButOOH, to C-H bond by insertion. For that mixed-chelate complexes of ruthenium have been synthesized using tridentate Schiff-base ligands derived by condensation of aldehydes (salicyldehyde, 2-pyridinecarboxaldehyde) with 2- aminobenzoic acid, and bidentate ligands (2,2'-bipyridine or picolinic acid). [RU"' ( ~ ~ s d ) ( b i p y ) ( ~ ~ ~[R) ]U'",' (cpsd)(pic)(H20)], [RU"' ( C ~ ~ C ) ( ~ ~ ~ ~ ) a(nHd ~ O ) ] ~ ' [ ~ u " ' ( c ~ ~ c ) ( p i c ) ( ~ z ~ ) l + complexes (where, c p s d 2 = ( ~ - (carboxyphenyl)salicylaldiminato); cppc-=N-2-carboxy phenyl pyridine-2- carboxaldiminato; bipy=2,2'-bipyridineand pic-=picolinate). Catalysis of hydrocarbon oxidations for cyclohexene, cyclohexane, cyclohexanol, toluene, benzyl alcohol, and tetrahydrohran has been studied using various 0-atom transfer agents (t-BuOOH, H202, NaOCl, KHSOs and pyridinium-N-oxide). A mechanism involving intermediacy of a high valent Ru(V)-0x0 species is proposed for the catalytic oxidation processes. Lobet et al. reported ' another exanlple of specitic catalytic activity of Cu (I) and Cu (11) di nuclear complexes of new hexa aza Schiff base macro cyclic ligands. It has been shown that these complexes are efficient and selective catalysts for the oxidation of 3,s-di-t-butylcatechol to 3,5-di-t-butyl- 1, 2-benzoquinone. Furthermore the measured initial rate constants reveal that it reacts much faster than any of the related macro cyclic systems. Applications of Schiff base complexes in the field of catalysis is not only limited to the field of chemical catalysis but it extend even to the field of biological catalysis. In this area report by Erskine et al. is very significant he^ studied about Schiff base complexes formed by the yeast 5-aminolaevulinic acid dehydratase with inhibitor laevulinic acid which has a specific role during catalysis. In the midst of sophisticated applications of Schiff base complexes in biological and selective catalysis, their role in traditional chemical catalysis cannot be under estimated. Following example is much relevant in this aspect. Nahar et al. reported catalysis of dehalogenation of chloroform by Schiff base metal complexes. Effect of metal ion on the dehalogenation of chloroform promoted by the ligand substitution reaction system, consisting of bis (N-n butyl salim) M (11) (M=Zn, Cu, Ni, Pt, Pd) and N, N, N'N'tetramethyl ethylene diamine is studied. Electro negativity of metal ion and stereochemistry of complex are found to control the rate of reaction. The next goal of this review is to demonstrate significant progress in the field of Schiff base co-ordination chemistry as it applies to medicinal field like drug designing diagnostic tool etc. This aspect has gained momentum in the development of molecule which have active role in treatment of diseases like cancer ' and neurological ' diseases and heart diseases (artherosclerosis) 9. Report of Cad on synthesis and biological activities of new Schiff bases of racemic gossypol and gossypolone and of (+) - and (-)-gossypol enantiomers and their Gold complexes is an interesting example. Schiff bases obtained fkom gossypol enantiomers are optically stable at room temperature whereas gossypolone Schiff bases racernize quickly and may be observed only at lower temperature. Their cytotoxic activities on human cancer cells were determined: it is suggested that gossypol and gossypolone dithianes and dithiolanes can be used as pro drug that target tumor cells. Verma et al. has reported anticonvulsant activity of schiff bases. They synthesized and screened Schiff bases of N-methyl and N-acetyl isatin derivatives with different aryl amines for anti convulsant activities against maximal electroshock (MES) and subcutaneous metrazole (ScMet). N-methyl-5-bromo-3-(p- chlorophenylimino) isatin exhibited anticonvulsant activity in MES and ScMet with LD(50) > 600 mg kg(-l), showing better activity than the standard drugs phenytoin, carbamazepine and valproic acid. Thus, compound N-methyl-5-bromo-3-(p- chlorophenylimino) isatin may be chosen as a prototype for development of new anticonvulsants. Toshihiko Takeuchi et al. have reported selective inhibition of Human 6 -Thrombin by Cobalt (111) Schiff base complexes. Human 6-thrombin associated with the blood coagulation cascade, converts fibrinogen into fibrin, which ultimately forms blood clots. Cobalt (111) Schiff base complexes of class (acacen) bind histidine residues in active sites and on enzyme surfaces in a random fashion. Spectroscopic and chromatographic evidence indicates that the binding of these complexes is controlled by axial ligand substitution. They showed that the reaction of active site- directed peptide linked to cobalt chelate leads to selective irreversible inhibition of thrombin. Other developments of interest in the areas of dnlg researck include the study of anti microbial activity of Schiff base and enhancement in activity due to complexation . Following studies show remarkable advancement in the respective fields. Dashora et al. reported 'O the synthesis of organo silicon and organolead complexes of Schiff bases from sulpha drugs. Complexes of the type (CH3)2Si(ONN) (C6&) 2Si(ONN), (C6&) 2Pb(ONN) have been prepared. New (N-indolidene-DL-glycine, N-indolidene-DL-alanine and N-indolidene- DL-valine) amino acid-Schiff bases by the condensation of indole- 3-carboxaldehyde and DL-glycine, DL-alanine and DL-valine were prepared and characterized by Nursen et al. l ' and their antimicrobial activities tested against four different microorganisms like B. subtilis, S. aureus, E. coli and C. albicans. The results of the antibacterial screening of the Schiff bases ind-gly, ind-ala and ind-val at a concentration of 5000 pglcm against all bacteria have been found and the results indicate that amino acid Schiff bases shows more activity against Staphylococcus aureus, E- coli and Bacillus polymyxa than Candida albicans. Ind-gly was found to be active against both strains of S. aureus. Escherichia coli and Bacillus poly myxa were inhibited by ind-gly. Ind-val was found to be the most active of them all. E. Coli was the most sensitive. The activity of these substances may be due to carboxyl group. The high activity of Ind-val may be due to the presence of electron donating effect. Acylhydrazine derived furanyl and thienyl Schiff bases and their Cu(I1) complexes were prepared l 2 and characterized by Zahid Chohan et al. The preferred enolic form of the Schiff base which function as a tetradentate ligand during coordination to the metal ion yields a square planar complex. The Schiff bases and their complexes with different anions were tested for their antibacterial activity against bacterial species such as Esclzericlzia coli, Staphylococcusaureus, Pselrdomonas aeruginosa and Klebsiella pneumonae. Raman et al. have synthesized l 3 and characterized neutral tetradentate complexes of Cu (11), Ni(II), Co(I1) and Zn(I1) using the Schiff base formed by the condensation of acetyl acetone and p-anisidine.. From the data it is found that all the complexes possess square-planar geometry. All the complexes were screened for antimicrobial activity against bacteria like S. aureus, E. Coli, B. subtilis and the fungus, A. Niger, by the well diffusion technique using DMSO as solvent. The minimum inhibitory concentration (MIC) values were calculated at 37OC for a period of 24 h. It is found that all the complexes are anti microbially active and show higher activity than fiee ligand. Modern researchers used to imitate the biosynthetic pathways by designing bio mimetic reactions that approximate natural reaction pathways. For example the relationship between redox properties and super oxide dismutase mimetic activity of thiohydrazone Cu (11) complexes was studied by Zdena et al. l 4 .The redox behavior of copper (11) complexes with the open chain ligand, benzil bis thiosemicarbazone, and the macrocyclic one [3,4,10,11-tetraphenyl-1,2,5,8,9,12,13- octaazacyclotetradeca-7,14-dithione-2,4,9,l1 - tetraene] has been explored by cyclic voltammetry. The half-wave potential values for the copper (II)/copper (I) redox couple and the spectral data obtained on dimethylsulfoxide (DMSO) solution agree with the super oxide dismutase (SOD)-mimetic activity of the complexes. The macrocyclic complexes show more positive reduction potential and more activity than the open chain derivatives. From their results it follows that the structure and conformation of ligand has influence on the redox potential of central atom in coordination compound. The changes in the coordination sphere are connected with the change of biological function of compounds represented by SOD-mimic activity. Iffet Sakyyan et al. l 5 have synthesized and characterized new complexes of Mn (111) with Schiff bases obtained by the condensation of 2-hydroxy-l- naphthaldehyde with glycine, L-Alanine, L-Phenylalanine, L-Histidine, L-Tryptophan and L-Threonine. These complexes are coordinated through the ONO donor set derived fiom the carboxyl, imino and phenoxy groups of the ligands. These complex molecules are proposed as model molecules where Mn plays an essential and specific role in water oxidizing complex of photosystem (11). Although manganese is essential for the oxygen evolution process in photosynthesis, its chemical role in photosystem I1 remains uncertain. Furthermore the chemical environment around the manganese ion is not known, which precludes the rational design of model compounds. The mechanism proposed , supported by flash photolysis data consist four discrete one- electron steps lead to oxygen evolution. Because of the multiplicity of the oxidation states of manganese and the associated coordination chemistry, it has an essential role as redox catalyst in photo system 11. In coherence with the advances in analytical chemistry Schiff bases have emerged as Cutting edge tools in sophisticated chemical analysis such as application of l 6 poly vinyl chloride (PVC) membrane electrodes based on two complexes of Schiff base 2,2'[4,4'-diphenylmethane bis (nitromethylidyne)] bis phenol, with copper (11) and iron (111) ions, and used for determination of tri iodide ions with lower detection limits of 4.0~10" and 6.0x10"mol dm-3, respectively. The proposed electrodes have fast response time (15 S) and their responses are independent of pH of the test solution in the range 3.5-9.0. The electrodes revealed very good selectivity for tri iodide ion over a variety of anions. They were used as an indicator electrode in the potentiometer titration of tri iodide ions and determination of ascorbic acid in Vitamin C tablet Optical pH sensor (optodes) based spectral response of newly synthesized Schiff bases " N, N-bis (4-diaminobenzy1iden)-1 ,2-cyclohexandiamine,N , hp-bis (4- diaminobenzy1iden)-l,2-ethanediamine and 2,6-bis [(4-dimethylaminophenylimino) ethyl pyridine is designed and tested. In most of the common designs, pH optodes rely on weak acidic dyes whose dissociated and undissociated forms have different absorption or emission maxima. In their work the newly synthesized Schiff bases have been used for pH sensing in four different plasticized PVC matrices. The Schiff bases exhibited absorption and emission based optical responses to protons in the pH range of 3.0-7.8, and, therefore, can be used as an optical pH sensor for near neutral region of pH scale. Copper in alloys can be safely estimated by using the Schiff base method without interference fiom many other metals in alloys. Elif Kormal and Esma KIIic used l 8 N, N'-disalicylidene-l, 3-diaminopropane as a selective chelating titrant for copper (11). The standard solutions of copper (11) (10"-10" M) were potentiometrically titrated using N,N-disalicylidene- 1,3-diaminopropane (Schiff base) as titrant and copper(I1)-selective electrode for end-point indication in both ammonium acetate and ammonialammonium chloride buffer media. The stoichiometry of titration reaction and interference effects of some metal ions on titration of copper was studied. There was a good agreement between the results obtained by the proposed titration method and ethylenediaminetetraacetic acid (EDTA) titration method. The accuracy and precision of Schiff base method were tested . In another report Papi et al. studied I9the synthesis characterization and application of metal complex of nickel with Schiff bases, 2-(2- pyridylmethyleneamino) phenol (PMAP) and 2-(2-quinolylmetl~yleneamino) phenol (QMAP). It was found that, for the Ni-PMAP complex, two ligands were bonded to one metal ion, giving a neutral complex with one molecule of water probably bonded in the inner sphere of the complex. In the case of QMAP, nickel forms cationic complexes with a metal-to-ligand ratio of 2:2 and two molecules of acetate as anions. The solution properties of Ni-QMAP were investigated at different pH. The chromophoric properties of the complex were enhanced with increase in pH, while stability decreased with time. The application of QMAP as a spectrophotometric reagent for the determination of small amounts of nickel was investigated. Adherence to Beer's law was observed fiom 0.00 to 5.00 pglml at pH 8, the most appropriate pH in respect to sensitivity and acceptable time stability of the complexes. Dyeing properties of both complexes were investigated on polyamide 66 and the influence of the addition of another phenyl ring to the ligand molecule on the dyeing properties of the complex is also investigated. Guidelines for the molecular design of non-doping red emissive materials for OLED applications are presented in the investigation of Jia-An Gan et al.. They have reported *O the synthesis of Schiff base derivatives of 1,8-Naphthalimides for non- doping OLEDs (organic light emitting diode) showing tunable emission color fiom blue, green to red Substitution at the 4-position of 1,8-naphthalimide with electron- donating groups can increase fluorescent quantum yields and change emissive wavelengths fiom blue to red . Based on this molecular design concept, novel naphthalimide derivatives containing Schiff base moiety were prepared by condensing 4-hydrazino-l,8-naphthalimidesw ith the aldehydes. Amino conjugation between the 4-amino-l, 8-naphthalimide and the substituted moiety resulted in red shift of the absorption and fluorescence maximum wavelengths in the aceto nitrile solution and in the net solid film. Some of these dyes emit brilliant red fluorescence in solid films and were used as non-doping emissive materials to fabricate electro luminescence devices. Review of Schiff base complexes of semicarbazones Like other Schiff bases semicarbazone are also excellent chelating agents. Diversity in structural aspects and predominance in applications like anticonvulsant, anti cancer and anti HIV activity might be the other reason for the vide study of semicarbazide complexes. A review with much priority for structure and synthesis follows. Dixit, Purnima et al. have synthesized 2' and characterized organotin (IV) complexes of acetoin and benzoin semicarbazones and thiosemicarbazones. By the condensation of benzoin and acetoin with semicarbazide hydrochloride and thiosemicarbazones corresponding Schiff bases are obtained. These when reacted with dimethyl tin dichloride and dibutyl tin oxide, lead to the formation of substitution products of the type, R2SnL (where R = Me or Bu and LH2 = ligand molecule). The resulting complexes have been characterized on the basis of elemental analysis, molecular weight determination and conductivity measurements. The mode of bonding of the ligands with the metal atom has been deduced on the basis of IR, 'H NMR and electronic spectral studies. All the ligands have been found to behave as bihnctional tridentate donors . Francisco Hueso-Urena have reported 22 the synthesis, spectral and XRD studies on three 0-nitrito-complexes with new N, N, 0-tridentate Schiff bases derived fiom 6-amino-5-formyl-l, 3-dimethyluracil and semicarbazide, acetylhydrazine and benzoylhydrazine From the reaction between Cu (11) and Zn (11) nitrates and three Schiff bases derived from 6-amino-5-formyl-l, 3-dimethyluracil and semicarbazide (H2SDO), acetylhydrazine (H2ACEDO) and benzoylhydrazine (H2BEZDO) in DMF, three nitrito-complexes with simplified formulas [Cu(HSDO)(N02)], [Cu(HACEDO)(N02)(H20)] and [Zn(HBEZDO)(N02)(1420)] have been obtained. In the three compounds the Schiff base acts as tridentate mono deprotonated ligand, making two five- and six-membered chelate rings. Agarwala et al. conducted 23 synthetic and physicochemical studies of uranium complexes with semicarbazone and hydrazones. Uranyl complexes of two Schiff bases, semicarbazone and hydrazones containing OON donor atoms have been synthesized .The coordination number of the o-vanillin semicarbazone (oVSC) complex is 6 whereas, that of the o-vanillin isonicotinic acid hydrazone (oVINAH) complex is 8, in addition to the two oxygen atoms already bonded to U (VI) in each species, The thermograms showed the presence of 3 and 2 water molecules in these complexes, respectively and the IR spectral data also supported the above conclusion. Vasile Lozan et al. 24 reported the synthesis of dinuclear nickel (11) and palladium (11) complexes with Schiff-base ligands (derived form salicylaldehyde condensed with 2-amino-l-alcohols or fiom 2-hydroxy-5-methyl isophthaldialdehyde and pyridine-2- carboxaldehyde condensed with semicarbazide, thiosemicarbazide, carbonodihydrazide, or thiocarbonodihydrazide) which can be activated with the co- catalysts methylalumoxane (MAO) or tris (pentafluorophenyl) borane for the vinyvaddition polymerisat ionof Norbornane. Singh et al. have reported 25 the synthesis of Schiff bases l-acetyl ferrocene thio semicarbazone and l-acetyl ferrocene semicarbazone by the condensation of 1- acetyl ferrocene with the corresponding thioscmicarbazide and semicarbazide hydrochloride, respectively. These Schiff bases on interaction with diorganosilicon (IV) chlorides yield complexes having Si-S or Si-0 and Si- N bonds. The structure of the ligands and their compounds have been elucidated .Spectroscopic data indicated that the Schiff bases act as bidentate ligands and coordinate to silicon via nitrogen and either the S or 0 atoms giving trigonal bi pyramidal and octahedral geometries for the resulting complexes. In another study Ferenc makkay et al. have discribed 26 the formation conditions, composition, stability and analytical application of some ternary complexes CO (11 ) :~ ' :~ (L1=aliphatic and alycyclic a-dioximes; x=N-~,I -), binary derivatives: co(11):L2 (L2=a-ketoximes diacetylmonoxime, methyl-isopropyl dione monoxime, 1,2,3-cyclohexane trione dioxime (1,3)), Co(I1): L3 (L3 = Condensation products of ketoximes with semicarbazide, thiosemicarbazide) and CO(II):L~ ~ ~ = ~ c h ibfafse s with ethylenediamine and hydrazine) were studied spectrophotometrically. The electronic spectra of these complexes were recorded and discussed. Leovac et al. have synthesized 27 octahedral CO (111) complexes with tridentate salicylaldehyde semi-thio semi -and iso thiosemicarbazone and pyridine of general formula [CO I11 (L )(py) 3 ] X , H 2 L ' = salicylaldehyde semicarbazone, X = [Co(II) Cl 3 (py)]- ,C10 4-.H 2 0 , I -. H 2 L = salicylaldehyde thiosemicarbazone, X = [Co(II) C1 3 (py)]', [Co(II) Br 3 (py)]- ,C1O4 -,H 2 0, I 3 - ; H 2 L = salicylaldehyde S- ethyl iso thio semi carbazone, X = [Co(II) Br 3 (py)]-,C10 i. H 2 O, BF 4- ). The tridentate coordination of all the three di anionic forms of the ligands involves the phenol oxygen, hydrazine nitrogen and the chalcogen ( 0 or S) in the case of salicylaldehyde semi-, thiosemicarbazone and the terminal nitrogen atom in the case of iso thio semi -carbazone. For all the complexes, octahedral arrangement is proposed, which is a consequence of the planarity of the chelate ligand. By using elemental analysis, molar conductivity, magnetic susceptibility, IR and electronic absorption spectra the compounds have been characterized. The thermal decomposition of the complexes was investigated by thermo-gravimetry, coupled TGMS and DSc. In another report 28 synthesis, physico chemical and voltammetric characterization of iron (111) complexes with pyridoxal semi-, thiosemi-and S-methyl isothiosemicarbazones are described .The reaction of warm EtOH solutions of FeX 3. nH 20( X =Cl, NO3 ) with tridentate 0 N X (X = 0, S, N) pyridoxal semi-?thio semi and S-methyl iso thio semicarbazones (H 2 L ' ,H 2 L ,H 2 L ,r espectively) yielded high-spin octahedral mono and bis(ligand)complexes of the formula [Fe(H 2 L )C1 2 (H 2 O)]Cl,[Fe(HL ) 21 Cl. nH 20 and[Fe(H 2 L )(HL;](NO~)~.H~OEl.e mental analysis, conductometric and magneto chemical measurements, and IR and UV-VIS spectra proved the stability and structure. Apart fiom the structural and theoretical point of application, complexes of semicarbazone posses high level significance in the applied chemistry. The following examples will provide the importance of semicarbazone complexes in advanced applications that are useful to mankind. Pandeya et al. have studied 29 anticonvulsant and neurotoxicity evaluation of 5-(un)-substituted isatin imino semicarbazide derivatives. Schiff bases were prepared by reacting 5-(un)-substituted isatin with some heterocyclic compound, viz., N- [4-(4'- chloropheny1)-thiazol-2-yl] semicarbazide, The compounds were evaluated for anticonvulsant and neurotoxin properties and found active. The above compound showed lower neurotoxicity than phenytoin and carbamazepine . i Elzbieta Pomarnacka et al. have reported 30 synthesis of l -(6-chloro- l , l - dioxo-l,4,2-benzodithiazin-3-y1)semi-carbazides and their transformation into 4- cl~loro-2-mercapto-~-(4,5-dihpdro-5-oxo-4-~1hH e-n l~ ,l2-, 4-tr ia3 .01-3-~1)be~~~~~ sulfona- mides as potential anticancer and anti-HIV agents compounds and these were tested at the US National Cancer Institute for their in vitro anticancer and anti-HIV activities. Results of anticancer screening showed moderate activity of and while was found to have encouraging anti-HIV activity. Schiff base complexes of 2-aminoplienol and 2 -aminothiophenol Review shows that higher tendency for chelation stability and diversity of the structure and speciality in applications are the reasons for wide interest in the Schiff base complexes of 2-aminophenol and 2-aminothiophenol. Salam et al. 31 has synthesized Cu (11) and Ni (11) complexes of some dibasic tridentate Schiff bases prepared by condensation of 2 aminophenol with 2-hydroxy- l -naphthaldehyde. Syamal et al. 32 have characterized Fe (111) complexes of tridentate Schiff bases derived fiom simple or substituted salicylaldehyde and 2-aminophenol. Tez Can has 33prepared and characterized the complexes of transition metals, rare earths metals and main group metals with Schiff base salicylidene 2- aminophenol and salicylidene -2-hydroxy - 1- naphthyl amine. The synthesis of several new coordination compounds of Cu (11), Ni (11), CO (11), Sn (11), Hg (11) etc with Schiff bases derived from 7 formyl-8- hydroxy quinoline (Oxine) and 2 aminophenol have been reported by Sonabati and bindarY3', the ligands and complexes were characterized by elemental analysis, IR, U.V, EPR, and NMR studies showed that the Schiff bases behave as mono basic and tridentate ligands coordinating through the oxygen atom of the deprotonated phenolic group, the nitrogen atom of the azonlethine group and pyridine. Schiff bases derived fiom salicylaldehyde and 2- aminophenol were synthesized and characterized by ~ a i aknd ~CO~ w orkers. Magnetic and electronic spectral studies provide the evidence for the existence of octahedral geometry for the complexes. Mehtha et al. 36 have synthesized Schiff bases derived fiom the condensation of 2 l~ydroxy-l- napl~thaldyhyde and 2-arninophenol. The copper complex was characterized by elemental analysis U.V, IR, NMR and magnetic data . New complexes 37 of the vanadium (IV) and oxovanadium (IV) with Schiff base ligands derived from the beta diketone and 2- arninophenol were prepared and characterized. A distorted octahedral environment was proposed for the vanadium (IV) and oxovanadium (IV) complexes. The spectroscopic results were used to compute the important ligand field parameters. Vanadium (IV) complexes exhibit promising catalytic activity towards the aerobic oxidation of phenylene diamine to the corresponding semi oxide form. Copper (11) complexes3*o f Schiff bases derived from equimolecular amounts of 5-nitro salicylaldehyde and the amines, 2 -aminophenol and 4-aminophenol were prepared by Murthy et al. . Copper complexes of the two ligands had a stochiometry 1:2. The complexes were tested for the anti bacterial activity against common pathogenic organism, and they showed mild to moderate activity . Jejukumar et al. 39haves ynthesized Schiff base complexes of Cu (11) and Ni (11) derived from phenyl butazone and 2- aminophenol. They were characterized by the elemental analysis, magnetic measurements, and X ray diffiaction and IR. The Schiff base ligands and their metal complexes were tested for their anti bacterial behavior using E. coli as a test organism. Chae et al. 40 have prepared the Schiff base ligands by the reaction of the salicylaldehyde and 2 hydroxy-l- naphthaldeyhde with 2-aminophenol and 2 amino- p- cresol respectively. The structures and the properties of the ligands and their CO (11) complexes were studied by using the elemental analysis, NMR, U.V IR, and TGA . The synthesis and characterization of the Schiff base from the 2-aminophenol and crocetinadialdehyde 2, 7- dimethyl octatrienedial or terephthaldehyde were carried out by Armin et al. 41. Maya Devi et al. 42 have synthesized and characterized some transition metal complexes of Schiff base quinoxaline-2-carboxaline-2-aminophenol. A tetrahedral structure was assigned for the Mn (11), CO (11), Ni (11) and Cu (11) complexes. For the Fe (111) complexes an octahedral dimeric structure was suggested . Platinum complexes43d erived fiom the 2- aminophenol and salicylaldehyde and 2 hydroxy-l- naphthaldyhyde were prepared and characterized by the elemental analysis conductance, magnetic measurements. IR and electronic spectral data. The tridentate dibasic nature of the ligand was established on the basis of IR studies,. The complexes are non-electrolytes, diamagnetic and square planar. Sanchez et al. have synthesized 44 new palladium (11) complexes with a tridentate PNO Schiff base ligand of aminophenol. Deprotonation of the Schiff base formed by condensation of 2-(diphenylphosphino) benzaldehyde with 2-aminophenol in the presence of the appropriate palladium precursor ([Pd (AcO) 21 or [PdClz (PhCN) 21) form the corresponding neutral complexes [Pd(2-(2-Ph~PC6H4- CH=N)C6H40)(Ac0)] or [Pd(2-(2-Ph2PC6H4-CH=N)C6H40)(inC 1g)o]o d yield. The frst reacts smoothly with thiols and activated phenols to give complexes of general formula [Pd (2-(2-Ph2PC6&-CH=N)c6H40)(X(X)] = OC6F5 , SEt , S~BU, , SC6H4-4Me , SC6&-4N02 ). When the chloro complex is treated with silver per chlorate and tertiary phosphines (L) the cationic derivatives [Pd {2-(2-PhzPCsH4- CH=N)C6&0)(L)][C104] (L = PPh3 , 13MePh2, PMe2Ph, PEt3 ) were obtained. The for the 1: 1 non-electrolytic complexes. Alumina-supported [M(haacac)] complexes catalyze the oxidation of cyclohexene with tert-butylhydroperoxide (TBHP). Schiff-base 2,5-pyrrolediyl bis [N-(o- hydroxyphenylaldimine)] (SBH2) has been synthesized by the condensation of 2,5-pyrroledicarboxaldehyde and o- aminophenol. The reactions of the Schiff-base with several transition- and post- transition-metal ions have been investigated. The Schiff-base reacts as a tetradentate dianion without deprotonation of the pyrrole. The complexes M (SB) nH20 have been isolated and characterized with n = 1,2 or 3; SB is the dianion of the Schiff-base ; and M = divalent Mn, CO, Ni, Cu, Zn, Pd, Cd, Pb or UOz. The binuclear complexes M (SB) MX2 for M = Cu, X =NO3, and M = Ni or Pd, X = Cl, have also been isolated by Tayim et al. 48. Besides the traditional applications, Schiff bases have emerged as analytical tool for precise determination of traces in even in physiological systems as the application of aluminium (111) 49 complex with salicylidene-o-aminophenol to the fluorometric determination of nucleic acids, is a very good devolopment in this field .In buffer medium of hexamethylene tetraarnine-HC1 at pH 5.9 the aluminium(III) complex with salicylidene-o-aminophenol (SAP) has a fluorescence peak at 508 nm with excitation at 410 nrn. When nucleic acid coexists, it reacts with the complex within 8 inin at room temperature to produce a non-fluorescent product, resulting in the decrease of fluorescence intensity of the aluminium complex. On basis of this. a new fluorometric method for nucleic acids determination is proposed. Compared with some established fluorometric methods. this procedure is sensitive, selective. reliable. and reproducible. Xiaoyuan Chen et al. has studied the synthesis 50 and structural characterizations of a series of novel '3+2' and '2+2+lt mixed-ligand complexes carrying 8-hydroxy-5-nitroquinoline (HL) as the bidentate N, 0 donor atom system. Thus, reactions of [ReOCl3(PPh3)2] with dianionic tridentate ligands H2Ln (where H~L'=Hoc~H~-~-cH=Nc~H~-~H-2Lo2H=;H0 C6H4-2-CH=N---~6~4-2-SH; H2L3=~0C6H4-2-CH=W=C(NHC~H~)---HS~H;L ~ = ~ - c H ~ o H - - - c ~ H ~ N - ~ - c H ~ ~ H ; and H ~ L ~ = ~ - c o ~ H - - - c ~ H ~ N - ~an-dc oH~LH a)ff orded a series of '3+2' oxorhenium complexes of the type [ReO(H2Ln)(L)]w hich exhibit distorted octahedral geometries. 1nvestigationss1 on new transition metal chelates of the 3-methoxy- salicylidene-2-aminothiophenol Schiff base have been carried out by Soliman et al. CO (11), Cu (11) and Zn (11) complexes of a Schiff base have been prepared and characterized by elemental analyses, IR, and 1H -NMR spectroscopy, thermogravimetric analysis, conductometric and magnetic measurements. The results suggested that the Schiff base is a bivalent anion with tridentate ONS donors derived fkom the phenolic oxygen, azomethine nitrogen and thiophenolic sulfur. The formulae were found to be [ML-H20] and [ML2] for the 1 : 1 and 1 : 2 non-electrolytic complexes, respectively. The thermal decomposition of the complexes follows first order. Complexes show ligand field transitions at 815 and 760 nrn at room temperature which are independent of the solvents used and are consistent with a pseudo tetrahedral kinetics and the thermodynamic parameters of the decomposition were calculated. Subrata Mandal et al. have reported 52 synthesis and characterization of CUNZS:!c omplexes for modelling the blue protein active sites. Two new tetradentate ligands have been synthesized by Schiff base condensation of di isobutyraldehyde disulphide with 2 -mercaptoethylaniine (L') and 2-aminothiophenol ( L ~r)e spectively and then reducing the imine linkages with NaBH4 in refluxing methanol. In the free ligands the thiolate sulphur is protected with tertiary butyl groups, which are cleaved in the presence of CU"-salts to give neutral CUNZSc~om plexes. Chinnasamy Jayabalakrishnan et al. studied 53 the products obtained by reacting ruthenium (11) complexes [RuHCl(CO)(PPh3)2(B)] [B = PPh3, pyridine (py) or piperidine (pip)] with tridentate Schiff base ligands derived by condensing salicylaldehyde or o-vanillin with o-aminophenol and o-aminothiophenol. Thesecomplexes have been characterized by analytical, IR, Electronic, 'H-n.m.r. and 3'~-n.m.r. Spectral studies and formulated as [Ru (L)(CO)(PPh3)(B)] (L = bifunctional tridentate Schiff base anion, B = PPh3, py or pip). An octahedral structure has been proposed for the new complexes. Some have been tested for the in vitro growth inhibitory activity against bacteria Escherichia coli, Bacillus sp. and Pseudornonas sp. Thangaian Daniel Thangadurai et al. 54 studied ruthenium (11) carbonyl complexes containing tetradentate Schiff bases such as bis anthranilic acid) acetylacetirnine (H2-anthacac), bis (anthranilic acid) dibenzoylmethimine (H2- anthdibm), bis(2-aminothiophenol) acetylacetimine (H2-2-amptacac) or bis(2- aminothiophenol) dibenzoylmethimine (H2-2-amtpdibm), with a general formula [Ru (CO)(LLf)(B)] (where, LL' = anthacac, anthdibm, 2-amtpacac or 2-amtpdibm; B = PPh3 or py or pip or morph) .The complexes have been characterised by elemental analyses and spectral (I.R. Electronic spectra, 'H- and 3'~-n.m.r.)d ata. An octahedral structure has been proposed for the complexes, which were also tested for their antibacterial properties. Schiff base complcxcs of keto compounds. For the last few years the properties and syntheic viability of cyclic ketones attract a keen attention to several scientists. Some of these complexes have very remarkable practical applications like anti cancerous, antibacterial activities etc A review of Schiff base complexes of keto compounds including those of dimedone, cyclohexanone and pyrolidone are presented here. Kamal et al. reported 55 the preparation and characterization of novel asymmetrical Schiff-Base ligands derived fiom dimedone with both ethylenediamine or p-phenylenediamine and 2-methyl-7- formyl-8-hydroxy quinoline and their metal complexes. These were prepared by reacting two half-unit Schiff-base compounds with 2-methyl-7-formyl-8- hydroxyquinoline. The two half-unit Schiff-base compounds were initially prepared by condensing dimedone with either ethylenediamine or p-phenylenediamine, respectively. Both ligands are dibasic and contain two sets of NO coordinating sites. Twelve metal complexes were obtained by reacting both ligands with Cu (11), Ni (11), CO (11), Mn (11), Fe (111), V 0 (IV) cations. The ligands and their metal complexes were characterized by elemental analysis; IR, UV-Vis, ESR ,mass spectra and magnetic moments of the complexes were determined. Visible spectra of the complexes indicated distorted octahedral geometries around the metal cations. ESR spectra indicated mononuclear and dinuclear structures of the complexes of ligands. Magnetic moments of the complexes were rather low compared with those expected for octahedral geometries and indicated polymeric linkage of the metal complex molecules within their crystal lattices. The insolubility of the metal complexes in most organic solvents supports the polymeric structures. Sergej et al. reported the biological activity of cobalt(II1) complexes with tetradentate Schiff bases and different biogenic nitrous bases or an analogous synthetic ligands. CO (aca~~en)(NH~)~a]nCdl .t heir analogs with different ligands were tested in vivo. Tumor-S response to treatment was estimated by standard methods. It was found all cobalt complexes have been shown to display substantial anticancer, in particular antimetastatic activity. Ahmed et al. 57 have synthesized Co(II), Ni(II), Cu(II), Zn (11), Cd(II), and U02 complexes of 5,5-dimethyl-1,3-cyclohexanoneb is(4-phenylthiosemicarbazone), H2CPT. These complexes have been characterized by elemental analysis, IR. and reflectance spectral studies, and magnetic moment measurements. IR. spectra show that H2CPT gives rise to dibasic quadridentate SNNS donor. Wang Dongmei et al. studied 58 about the reaction of metallic copper powder with 2-thenoyltrifluoroacetone and bis (diphenylphosphino) ethane which gave the binuclear copper (I) complex [Cu (dppe)(tfac)12. The complex has been characterized by physico-chemical and spectroscopic methods. X-Ray structure of the title complex shows that 2-thenoyltrifluoroacetone behaves as chelating ligand and dppe coordinates as bridging ligand to CU' atoms in the newly prepared copper complex. Kozlov et al. have reported 59 synthesis of benzo phenanthridine derivatives by condensation of N-Arylmethylene-2-naphthylamines with 5-Phenyl- and 5-(p- Methoxypheny1)- l ,3-cyclohexanediones. Condensation of N-arylmethylene-2- naphthylamines with 5-phenyl- and 5-(p-methoxypheny1)-1,3-cyclohexanediones in various solvents gave new hexahydrobenzophenanthridin-4-one derivatives. Casas et al. have studied 60thec rystal and molecular structures of cyclohexanone thiosemicarbazones . It crystallizes in the triclinic crystal system and the following unit cell parameters: a = 6.2989, h = 7.97, and c = 9.41 A' ; a = 79.60 O , P = 85.519 O and y = 73.50'. Agarwal and Sharma synthesized 6' some novel Cu (11) complexes of biologically important hydrazones of isonicotinic acid hydrazide various hydrazones of isonicotinic acid hydrazide (INH) were isolated by condensing isonicotinic acid hydrazide with various aromatic ketones, viz, benzophenone (BPN). cyclohexanone (CHN) or benzylacetone (BzAN). The interaction of these hydrazones with Cu(1I) salts in non-aqueous solvent resulted in the coordination complexes with the general composition CuX2 2L (X = Cl. Br, NO3 or CH3COO and L = INH-BPN, INH-CHN or INH-BzAN).These complexes were characterized through elemental analyses. electrical conductance, infrared and electronic spectra.Biologica1 activity of these complexes were also investigated. Scope of present investigation Literature survey shows that the study of coordination compounds especially those of Schiff base are highly relevant. Wide range of applications of Schiff base complexes in general and those of semicarbazone, 2-amino phenol, 2-amino thiophenol,cyclohexanone, dimedone etc in particular give us great hope for the future research which may be useful to mankind. The dull period in the history of Schiff base complex in the 1990s has give way to the uprising in the new millennium especially regarding the advanced application in drug designing, as analytical tools and for asymmetric catalysis. Hence the decision to go for synthesis and investigations on Schiff bases and their complexes with new combination of semicarbazone, aminophenol and aminothlophenol, has much relevance. The survey has also revealed that Schiff bases of keto compounds are very rare. So new combination of Schiff bases involving keto compound such as dimedone, cyclohiexanone and pyrolidone with semicarbazide, aminophenol and aminothiophenol were studied. And their complexes of transition d block elements were prepared. For the characterkition of ligands and complexes data from elemental analysis by IR, UV, NMR ,magnetic and conductance studies were used. Kinetics of thermal decomposition is studied using the TG. In application level anti fungal activity of the ligands and representative complexes are tested. The anti fungal activity of the co-ordination compounds on certain fungi like Phytophthora capsici which may contribute to development of specific fbngicide for the crop protection. CHAPTER 2 MATERIALS AND METHODS In this chapter a concise report of the reagents, apparatus used and the methods adopted for the synthesis, characterization of the ligands and complexes are presented. Detailed descriptions are provided in suitable contexts. Materials and methods for antifungal studies are given as a separate chapter in part 111. 1) Chemicals: Analar grade chemicals (BDH, E.Merck, Glaxo) are used for the synthesis. For the preparation of the ligands reagents Dimedone, 2-Aminothiophenol, 2-Aminophenol, Cyclohexanone and Pyrolidone were used. The metal salts used for the synthesis of the complexes are acetates of Mn (11) CO (11), Ni (11), Cu (11), Zn (11) and Cd (11). The solvents used for the synthesis, purification and analysis of ligands and complexes are ethanol, methanol, acetone, diethyl ether, petroleum ether, and dimethyl formamide and dimethyl sulphoxide. Solvents ethanol and methanol are purified by standard methods 62. 2) Synthesis of ligands and complexes The procedures for the preparation of the ligands and complexes are given in the following chapters. 3) CHN analysis Carbon, Hydrogen, and Nitrogen content of the ligands and their metal complexes were determined by microanalysis on PERKIN ELMER CHNS/O analyzer 4) Estimation of metals Standard methods 63,64 like volumetric, gravimetric or pyrolytic techniques were adopted for the estimation of metal content. The atomic absorption spectroscopy is also used for the conformation of the metal percentage in selected samples. For the volumetric and gravimetric estimations, a common method was used for decomposing the metal complexes. About 0.2 g of the complex was digested with concentrated nitric acid -perchloric acid mixture followed by con. FIC1. The resultant solution was then quantitatively made up to 100 ml. By using a definite volume of the solution the metal content of the complex was estimated. Amount of the copper was determined iodometrically by the addition of K1 and subsequent titration of liberated iodine by standard sodiumthiosulphate. Cobalt and cadmium were estimated volumetrically by complexometric titration using standard EDTA solution and xylenol orange indicator. Gravimetrically nickel was estimated by precipitating as dimethyl glyoximate. Zinc and Manganese were estimated by complexometric titration using standard EDTA and eriochrome black T indicator. Almost all of the metals were estimated by pyrolysis method. About 0.2 g of each complex was weighed out in a silica crucible and heated strongly. During the heating all the organic particles in the chelate was burnt off and the metallic oxide left behind was weighed. From the weight of the oxide metal percentage was calculated. 5) Electrical conductance Molar conductance measurements of the complexes were carried out in nitrobenzene or DMSO solvent at 2 5 ' ~* 2 ' ~on a Toshniwal conductivity bridge Approximately 1 0 " ~so lutions were used for these studies. 6) Magnetic measurements Magnetic susceptibilities of the complex were determined at room temperature by Gouy method. 6566 Diamagnetic corrections were applied using Pascal's constants taking into consideration of the magnetic contribution of the various atoms and structural units. Effective magnetic moment was calculated from the corrected molar susceptibility equation. pen~ 2 . 8 4d( Yr'IIIT) YJ',=molar susceptibility corrected for diamagnetism and T = absolute temperature. The theoretical magnetic moments were calculated using the formula pn= gd (S (S+l)). 7) Infra red spectra The infia red spectra of the ligands and metal complexes were recorded in the range 4000-400cm~'nm on a Shimadzu -1R 470 infra red spectrophotometer by KBr disc technique .The importance of IR spectroscopy lies in the fact that the characteristic infiared absorption bands of a group occur at about the frequency irrespective of the molecule in which the group is present. 8) Electronic spectra The UV - Visible spectra of the ligands and complexes were carried on a Shimadzu recording spectrophotometer using DMSO as solvent. For each complex, the peak was assigned to a particular d-d transition. Electronic spectral studies were used to supplement the information obtained fiom magnetic measurements. 9) Thermo gravimetric analysis Thermo gravimetric analysis was carried out on a PERKIN ELMER 7 series thermal analyzer in static air atmosphere maintaining the rate of heating at 10Ocmin-l. 10) NMR spectra NMR spectra of ligands and complexes of selected complexes (Zn (11) and Cd (11) complexes of H2PAP, H2PATP , H2 CAP and H2CATP) were carried on Brucker DPX 300 MHz machine using DMSO as solvent. In each case the spectra were analyzed by considering the standard chemical shift values 11) 3D sketches and Naming of ligands For the naming of the ligand molecules and the drawing of 3d structures the 'Chem. Sketch' soft ware by Advanced Chemistry Devolopment Inc is used. For the naming of the ligands same software with the norms of Jozirnal ofAmerican Chemical society is used. In the 3D drawing of the complexes, the stereo chemical factors are not considered since the parameters tested was in sufficient to explain the exact stereochemistry of the molecule. CHAPTER 3 Studies on Mn (11), CO( 11), Ni(II),Cu(II),Zn(II) and Cd(I1) Complexes of Dimedone bis Semicarbazone (H2DSC) During the past few decades, major developments have been achieved in the research of coordination compounds with special emphasis on metal complexes of Schiff bases containing nitrogen and oxygen donors 67-71 . This may be due to their stability, biological a ~ t i v i t ~ ~ ' , ~p~otaentdia l applications in many fields7 5, 76 . Biological activity of complexes derived fkom semicarbazide has been widely studied 71 and contrasted for processes such as, antitumor, antiviral, anti malarial and anti tuberculosis activities. 71,72, 73,74 We have attempted to synthesise a novel ligand dimedone bis semicarbazone and to explore its possibilities as active and potential biological agent. With the aim of further research complexes of semicarbazone of dimedone were synthesized. Semicarbazone of dimedone can act as a tetradentate dianionic ligand containing the ONNO donor group. Besides two azomethine groups the ligand contains two-carbonyl oxygen, which are enolisable and hence act as potential donor sites. A perusal of literature shows that studies about Schiff base complexes of dimedone are very rare and those of semicarbazide are a few in number 23,30,59,77,78 . But complexes of H2DSC are not reported so far and hence seeks a special attention. So it seems to be very essential to synthesize and characterize the complexes of dimedone bis semi carbazone and to conduct detailed investigation about the structure, magnetic properties, thermal stabilities, decomposition patterns and biological activities of these complexes. A. Experimental 1. Materials and methods Specifications regarding the reagents used the procedural details adopted for the characterization of the ligand and complexes are given in chapter 11. 2. Preparation of ligand - Dimedone bis semicarbazone A hot ethanolic solution of dimedone (0.0 l m01 ) was added drop wise to a stirred solution (0.02 m01 ) of semicarbazide dissolved in 20ml of water and 20 m1 of ethanol. The mixture was refluxed for about 15 minutes and then cooled .The pale yellow precipitate formed was filtered, washed with alcohol and then dried. To obtain dimedone bis semi carbazone a hot saturated solution of it was neutralized with very dilute solution of sodium hydroxide. As the solution was cooled pale yellow crystals of dimedone bis sernicarbazone got separated. 3.Synthesis of complexes of Dimedone bis Semicarbazone The complexes were prepared by adding slowly a hot aqueous solution of the metal acetate to a refluxing ethanolic solution of the ligand containing sodium acetate (0.5gm) until the metal ligand ratio reached 1: 1 . The reaction mixture was refluxed for one hour and the complexes were precipitated. The complexes were washed with water followed by ethanol and dried over anhydrous Ca Ch. The complexes of Mn (11), CO (11), Ni (11), Cu (11), Zn (11) and Cd (11) were prepared by the above method. B. Results and discussion Analytical and physicochemical data obtained, have been correlated in a logical way to explain the properties, structure and bonding in the compounds. 1. Characterization of Ligand TLC established the purity and homogeneity of the ligand. CHN and IR data given in the Table 1.3.1-1.3.2. showed close agreement with empirical formula for dimedone bis semicarbazone. The structure of H2 DSc is given in figure 1.3.1. 2. Formulae and general properties of complexes All the complexes are colored, stable and non-hygroscopic. The solubility of these complexes in common organic solvents are very low but they are soluble in DMF and DMSO. The values of electrical conductivity of these complexes in DMSO showed that they are non-electrolytic compounds. The complexes were analyzed for metal, estimated by using atomic absorption spectroscopy and carbon, hydrogen and nitrogen estimated by standard micro analytical methods. The analytical data of the complexes corresponds to the formulae ML (H20) 2 where M = Mn (11), CO (11), Ni (11), Cu (11), and ML where M = Zn (11) and Cd (11). Results are given in the Tables 1.3.1- 1.3.3. 3. Magnetic behavior Magnetic measurements are extremely useful in the structural determination of inorganic coordination compounds 79380, Here the magnetic susceptibility of complexes were determined by the Gouy balance. The measurements were made at room temperature. The Gouy balance was standardized using Hg [CO(NCS)~a] s calibrant 'l. Table 1.3.1 shows effective magnetic moment values calculated from the corrected magnetic susceptibility. When a sample is weighed in the presence and absence of magnetic field a weight change is observed. Diamagnetic materials have no unpaired electrons and show a slight decrease in weight. Paramagnetic materials have unpaired electrons and they show an increase in weight in presence of magnetic field. From this change in weight the paramagnetic susceptibility and effective magnetic moment can be calculated . The magnetic moment values provide information regarding the number of unpaired electrons present in a molecule and orbitals in which they are situated. Some indications of the structures and geometries of the complexes are also obtained fiom magnetic moment values. 79 In the case of Mn (11) complex the electronic d-d- transition fiom a high spin d5 configuration must necessarily involve the pairing of some electron spins, such transitions are both spin forbidden and orbitally forbidden, therefore the bands are weak. Octahedral geometry is common among high spin d5 configuration and spin only magnetic moment in the range 5.9 BM is expected *'. The HzDSC complex shows a moment of 5.85 BM indicating d5o ctahedral geometry. Octahedral and tetrahedral CO (11) complexes differ in their magnetic properties. In high spin octahedral complexes of CO (11), ground term is 4 ~ l g which results in considerable orbital contribution. Hence the observed magnetic moment values are in the range -5.20 BM which is higher than the spin only value for three unpaired electrons. 79380 The low spin octahedral CO (11) complex has ground state 2 ~ h,en ce no orbital contribution is expected. So the observed values are very close to the spin only values for 1 un paired electron (1.73 BM). In tetrahedral high spin complex of CO (11) the ground term is 4 ~ a2nd there is no orbital contribution. The expected magnetic moment is the spin only value for the three unpaired electrons i.e. 3.87 BM. However observed values are in the range 4.40-4.80 BM. The high value is due to spin orbit coupling perturbations. In the case of four coordinated low spin complexes, which are square planar, it is difficult to predict accurately the magnetic properties. A magnetic moment rather above the spin only value for unpaired electron 1.73 BM is expected 79380 The CO (11) complex of H2DSC shows magnetic moment of 4.89 indicating octahedral geometry, which is hrther supported by electronic spectral data . When we are considering the magnetic properties of the complexes of Ni (11), it can be classified in to three categories 79,80. Six coordinated octahedral complexes with paramagnetic character and 3 ~ 2 gg round term, four coordinated square planar diamagnetic complexes with a spin singlet ground term and the four coordinated approximately tetrahedral paramagnetic complexes with a triplet ground term. Between the two paramagnetic types the octahedral complexes show magnetic moments in the range 2.90-3.30 BM, because no orbital contribution is expected, as the ground term is 3 ~ 2 g . A slightly higher value than the spin only moment is expected for the complexes because of the spin orbit coupling or higher state mixing with ground state .8 0 For tetrahedral complexes the magnetic moment values are in the range of 3.20-4.00BM. The higher value is due to the appreciable orbital contribution of the T ground state. Large distortions and inequalities in the field of coordinated ligands may result in magnetic moments with small orbital contributions and the observed values are as low as 3.20 BM. Square planar complexes have a spin singlet ground state and hence are diamagnetic. The Ni (11) complex of HzDSC shows a magnetic moment of 3.1BM, which indicates an octahedral geometry, which is further supported by electronic spectral data. The Cu (11) complexes usually have a distorted octahedral stereochemistry. A few are known with square planar or approximately tetrahedral geometry. But stereochemistry has little effect on the magnetic moment of Cu (11) complexes and magnetic moment is about 1.90 BM. In regular octahedral Cu (11) complexes ground term is 2 ~ agnd hence no orbital contribution is expected. The spin only magnetic moment value corresponding to one unpaired electron is 1.73 BM, but the observed values fall in the range 1.80-2.10 BM. The slightly higher value is due to the spin orbit coupling. In regular tetrahedral Cu (11) complex the ground term being a triplet state, orbital contribution is expected and theoretically predicted value of magnetic moment is 2.20 BM " . But the reported values are in the range 1.95-2 BM '' .The observed magnetic moment values of Cu (11) complexes of H2DSC is 1.77BM which indicates octahedral geometry of the Cu (11) complex. 4.IR spectra Among the different analytical techniques, Infrared spectroscopy is one of the powerful methods for structural analysis. It can be used for the identification and characterization of a compound and assigning structures. The significant vibrational bands and their assignments of the ligand and the complexes are given in the tables. Assignments are made on the basis of comparison with similar known systems 84. IR spectra of H2DSC shows band at 1613 cm-' and 1671 cm-' which are due to C=N stretching and C=O stretching respectively 84. The band at 3350 cm-' is probably due NH stretching and that at 3450cm" is probably due to stretching of NH2 groups 84 .The IR spectra of the complexes are compared with that of the free ligand to determine the changes that might have taken place during the complexation. The band at 1613 cm-' is the characteristic of the azomethine group present in the free ligand. The lowering in this frequency region (1543 - 1599cm -' ), observed in all the complexes, indicates the involvement of the ammethine nitrogen atom in coordination 85y86. The band at 1671 cmP'is characteristic of the C=O in the free ligand. In all the complexes this band disappears and new band appears around 1000cm-' due to y C-0. This may be due to enolisation and subsequent coordination of this carbonyl group87.~hbea nd at 3350 is assigned to the >NH stretching, this band disappears in all the complexes, supporting enolisation. Ligand shows absorption at the frequency 3450cm" which may be assigned to the NH2 stretching 84. The bands at 521-517 cm-' and 424-418 cm -' are due to the formation of M-N and M-0 bonds respectively. 84,88 Presence of a broad band around 3447 cm-' (except in Zn (11), Cd (11) complexes) may be due to the OH stretching of coordinated water. But in some of the complexes this band are not obvious due to the overlapping of some other bands 84388. In addition to that a medium band approximately at 944-966 suggests that the water molecules are coordinated . The characteristic frequency of free acetate ion 84,89 at 1560, 1415 are absent in all the complexes. But the non-conducting nature and stoichiometry of this complex indicate that acetate ion is not present in them. 5.Electronic spectra The electronic spectra of all the complexes of H2DSC are recorded in DMSO. The important spectral bands of the complexes and their probable assignment are given in the Table.I.3.3. The electronic spectrum depends on energy of metal d orbitals, their degeneracy and the number of electrons distributed. These features in turn are controlled by the oxidation state of the metal, number and kind of the ligand and the geometry of the complex 90. The majority of Mn (11) complexes have high spin octahedral d5 configuration. A high spin octahedral field gives spin forbidden as well as parity forbidden transitions. Hence octahedral Mn(I1) complexes are usually pale in color and the absorption are very weak. The tale of CT bands overlap with weak transition thus obscuring them. In tetrahedral environments the transitions are still spin forbidden but no longer parity forbidden. These transitions are there for about 100 times stronger and complexes have noticeable light yellow green color 91. In the present investigation Mn (11) complex of H2DSC shows a number of weak bands which may be assigned to charge transfer or d-d transition in octahedral field. Octahedral geometries are commonly found in CO (11) complexes and such complexes are pink in color. The expected d-d transitions are 92,93,94 T (F) -+ T (F) = - 1250-1000 D 'T~, (F) + $,(F ) -= 880 nm T (F) + A (F) === 700-500 nm T l g( F) + l (p) ===== 500-400 nm However the visible spectrum will be dominated by the highest energy transition and spectrum is usually complicated by poor resolution of several of these bands. This makes the assignment of this spectrum somewhat difficult. Tetrahedral CO (11) complexes are generally deep blue in color and expected transitions are Both environments give rise to bands in the same region around 500 nm, although tetrahedral complexes more frequently exhibit maxima near 700nm. So the best spectral indicator of stereochemistry is the intensity especially when the spectrum is complicated by the overlap with a strong charge transfer tail. For square planar complexes which are generally dark brown in color weak and broad bands are present in the region 1200 - l000 nm. In the present investigation CO (11) complex shows absorptions which can be assigned to the d-d transitions of octahedral geometry as given in the Table.I.3.3. Low intensity of bands and purple color support octahedral geometry. Studies by Jorgensen revealed that in the case of Ni (11) 96 four bands corresponding to the transitions are observed in the given ranges 3 ~ 2(Fg) -, 3 ~ 2(gF ) - i loo -900 nm 3 ~ 2 g(F ) -+ (F ) -800-750 nm 3 ~ 2 g(F ) -, 3 ~ l g(F ) -650-520 nm 3 ~ 2 g(F ) -, 3 ~ l (gP ) -400-350 nm The ratio of the wave numbers of the first and third band lies in the range 1.6 -1.8 that is one of the distinguishing characteristics of octahedral Ni (11) complexes. Most of the tetrahedral complexes of Ni (11) have intense blue color due to the presence of an absorption band in the red part of the visible region. The occasional appearance of green or red color in tetrahedral complexes is due to the charge transfer absorption tailing in to the visible region from the ultra violet region. The two readily accessible bands in the spectrum of tetrahedral Ni (11) complexes are 3 ~ (1F) + 3 ~ (F2) 1250-15 00 nrn 3 ~ (F1 ) --+ 3 ~ (1P) 700-600 nm 3 ~ (F2 ) -+ 3 ~ 1 (3~30)0- 2000 nrn The third band is usually over lapped by absorption of organic part in the molecule or the solvent The square planar complexes of Ni (11) 96 are generally red yellow or brown and this may be due to the presence of absorption bands of medium intensities. However other colors do occur when additional bands are present. 97 The different bands and the assignments are the following 97,98,99 'Alg - 600-570 nm l ~ l -g-t1 A2g - 480 nm 'Alg -+'Eg - 400nrn CT bands usually overlap the second and third bands In the present investigation Ni (11) complex of H2DSC shows three absorption bands which are assigned as given in the Table 1.3.3 and obtained data support the octahedral geometry. The ratio of wave numbers of transitions 3 ~ 2 g (-~*)3 ~ 2 g) ( ~- 9 29 3 ~ 2 g (+~3) ~ l g () ~ -512 is in the range 1.6 to 1.8 which confirms the octahedral geometry. For octahedral Cu (11) complexes only a single band due to the transition 2 ~ g2-~ 2 gw ould result but the observed band is very broad and clearly contain several components which is a result of tetragonal distortions due to Jhan -Teller effect . In tetrahedral Cu (11) complexes d-d transition occur in the range 1400- 1000 .In square planar and octahedral complexes band appears in the region 1000- 500 . If this region is blank then it can be inferred that the complexes are tetrahedral in nature. It can also be inferred that the complexes have tetrahedral geometry if the energies of the bands are low compared to those of square planar or tetragonal complexes. A greenish blue color is associated with penta or hexa coordinated Cu (11) and brown and violet color indicate 4 coordinate Cu (I1) lO0,lOl In the case of the Cu (11) H2DSC complex an absorption band present 674 nm is assigned to the d-d transition in octahedral complexes. 6.Conclusion The complex compounds of Mn (11), CO (11), Ni (11), Cu (11) , Zn(I1) and Cd(I1) with dimedone bis semicarbazone are synthesized . The physico chemical properties of all the complexes were studied . The complexes have the general formula [M (L)(H20) 21 where M= Mn (11) CO (11) Ni (11) Cu(II), and L is tetra dentate di anion obtained fiom H2DSC(H2L ) . The other complexes are assigned the formula [ML] where L is the tetra dentate di anionic ligand obtained fiom HzDSC [H2L] and M=Zn (11) or Cd (11) . In all metal complexes the carbonyl group is enolised and ionizes and then coordinated to the metal ion. The IR data, conductance values and stochiometry of the compound strongly prove this assumption. The data obtained are insufficient to prescribe the exact geometry of Zn (11) and Cd (11). However in comparison with structure of other complexes and considering common coordination numbers exhibited by these metal ions, a four coordinated tetrahedral geometry may be assigned to them . 7.Structure of Ligand and complexes By considering the analytical data the structure of the ligand Dimedone bis semicarbazone and its Mn (II),Co (11), Ni (II),Cu(II),Zn (11) and Cd (11) are drawn . The proposed structure is given in Fig 1.3.2 and 1.3.3. Ligand Figure I. 3 .1 Octahedral Complexes Complexes of H2DSC where M = Mn(II)Co(II),Ni(II),Cu(II) Figure 1.3.2 Tetrahedral Complexes Complexes of H2 D S c where M = Zn(II)Cd(II). Figure 1.3.3 Table 1.3.1 Micro analytical, magnetic and Conductance data of transition metal chelates of Dimedone bis semicarbazone ( H2DSC) Complexes Conductance Molecular Found (calculated)% Compound peffective formula Metal H2DSC(LIGAND) D= diamagnetic Table 1.3.2. Characteristic Infrared absorption frequencies (cm-')of transition metal chelates of H2DSC Table 1.3.3 Characteristic ultraviolet frequencies and probable assignment of transition with geometry of HzDSC complexes Complex Band(nm) Assignment Geometry [Mn L (H201 21 412 CT Octahedral 1075 4 ~ 1 (gF ) + 4 ~ 2 (gF ) [COL (H20)21 Octahedral 666 4 ~ 1 (gF ) -+ 4 ~ 2 (gF ) 929 3 ~ 2 g (-~+)3 ~ 2(gF ) [Ni L(HzO)21 5 12 Octahedral 3 ~ 2 g (d~3)T l g( F) Distorted [CuL(H20)21 674 2 QP2T2g octahedral [ZnL] 395 CT Tetrahedral 323 CT [CdL] Tetrahedral H E D W COMPLEXES OF &D8 CHAPTER 4 Studies on Mn (II), CO( 11), Ni (II),Cu(II),Zn(II) and Cd(I1) Complexes of Dimedone bis-2-Aminothiophenol (H2DATP) and Dimedone bis -2 Aminophenal (H2DAP) Two Ligands dimedone bis-2-aminothiophenol (H2DATP) and dimedone bis -2-aminophenol (H2DAP) have been synthesized for the first time. These two novel ligands form various complexes with different transition metal ions. Both ligands are found to be tetradentate. Schiff base complexes of aminophenol 50-,54 and aminot hioph eno l 47-49 ,102 are widely studied. Literature survey reveals that not much work has been done on the Schiff bases derived fiom 5,5 dimethyl 1,3 cyclohexanedione (dimedone), and dimedone bis-2-aminothiophenol (H2DATP), and dimedone bis -2-aminophenol (H2DAP) are the ligands reported for the first time. In this chapter detailed investigation of the ligands H2DAP and H2DATP were made with a special attention on structure, magnetic property, thermal stabilities, decomposition patterns and biological activities of these complexes derived fiom them.. Here H2DAP can act as a tetra dentate dianionic ligand containing the ONNO donor group while H2DATP can act as a tetra dentate dianionic ligand containing the SNNS donor group. A. Experimental 1. Materials and methods Specifications regarding the reagents used and the procedural details adopted for the characterization of the ligand and complexes are given in chapter 2 2.Preparations of ligands H2DAP and HzDATP A hot ethanolic solution of dimedone ( 0.0 l mol) was added drop wise to a stirred solution contaning.02 m01 of 2 aminophenol dissolved in ethanol. The mixture was refluxed for about 20 minutes and then cooled. The pale yellow precipitate formed was filtered, washed with alcohol then dried. Melting point 141°c.~ob tain H2DATP the same procedure adopted for H2DAP is used. Melting point 1 3 0 ' ~. 3. Synthesis of complexes of H2DAP and H2DATP The complexes were prepared by adding slowly a hot aqueous solution of the metal acetate to a refluxing ethanolic solution of the ligand until the metal ligand ratio reached l :1 . The reaction mixture was refluxed for 45 minutes and the complexes precipitated were separated. It was washed with water followed by ethanol and dried over anhydrous Ca Ch. Complexes of Mn (11), CO (11), Ni(II), Cu(II), Zn(I1)and Cd(I1) were prepared by the above method . B.Results and discussion The complexes were characterized on the basis of elemental analysis, UV and IR spectral data, magnetic studies, conductance measurements and the thermal data 1. Characterization of Ligand TLC established the purity and homogeneity of ligand. CHN, and IR data given in the Table 1.4.1-1.4.5 showed close agreement with empirical formula for H2DAP and H2DATP . 2. Formula and general properties of complexes All the complexes are colored, photo stable and non-hygroscopic. The solubility of these complexes in common organic solvents are very low but they are soluble in DMF and DMSO. The values of electrical conductivity of these complexes in DMSO show that they are non-electrolytic compounds. The complexes were analyzed for metal estimation by using atomic absorption spectroscopy and carbon hydrogen and nitrogen estimated by standard micro analytic methods. The analytical data of the complexes corresponds to the formulae ML (H20) where M= Mn (11), CO (11), Ni (11), Cu (11) and ML where M= Zn (11) and Cd (11) Results are given in the Table 1.4.1, -1.4.6. 3. Magnetic behavior The details of the methods for theoretical prediction by magnetic behavior of complexes are already explained in the chapter 111. The observed magnetic moment values are summarized in Table 1.4.1 and 1.4.4. The Mn (11) complexes are showing magnetic moment values 5.91 and 5.97BM (H2DAP,H2DATP)i ndicating octahedral geometry with high spin d5 configuration. The observed magnetic moments for the spin free octahedral CO (11) (4~1gis) higher than spin only values and it may be due to orbital contribution of both the ground state (t22e:) and the first excited state (t2ied). It is reported that the octahedral high spin geometry can be assigned to Co(I1) complexes, if the observed magnetic moment values are in the range of 4.7 -5.2 BM 'O. The cobalt (11) complexes of H2DAP and H2DATP possess magnetic moment values of 4.9 and 4.8 BM that proves the octahedral geometry. The H2DAP and H2DATP complexes of Ni (11) have magnetic moment value of 3. 1 BM and 3.01 BM which is very close to the spin only value of octahedral geometrya0.T he magnetic moment of Cu (11) complexes of H2DAP and H2DATP possess normal values 1.97BM and 2.1 B.M as expected for octahedral geometryaOl~o3 . The Zn(I1) and Cd (11) complexes are found to be diamagnetic. 4. IR spectra H2DATP shows bands at 1610 cm-' and 2650 cm-' which are due to C=N stretching and S-H stretching'04 respectively. The band at 701 cm-' is probably due C- S stretching '04.~heIR spectra of the complexes are compared with that of the fiee ligand to determine the changes that might have taken place during the complexation. The band at 161 0 cm-'is characteristic of the azomethine group present in the fiee ligand. The lowering of this fiequency to the region (1582 - 1589cm -l), observed in all the complexes, indicates the involvement of the azomethine nitrogen atom in coordination 85.86 The stretching vibrations of (SH) have no apparent help since they display very weak bands in both the fiee and in the complexes however, the participation of SH group in chelation is ascertained fiom the shift of y C-S fiom fiequency fiom 701 cm-'. ".lo4 The bands ranging fiom 418 to 450 cm -' are due to the presence of M-N bonds 84,88. Presence of a broad band around 3447 cm-' in the case of Ni (11), CO (II),Mn(II) and Cu(I1) may be due to the OH stretching of coordinated water' The presence of OH bending frequency at 931 to 937 cm -1 104 ,51 further confirms the presence of coordinated water. The characteristic fiequency of fiee acetate ion at 1560 and 1415 cm -' are absent in all the complexes. 84189 The non conducting nature and stoichiometry of this complex indicate that acetate ion is not present In IR spectra of H2DAP bands at 1605 cm-' and 3450 cm-' are due to C=N stretching and 0-H stretching respectively 84.T he band at 1240 cm-' is probably due to C- 0 84. The IR spectra of the complexes are compared with that of the fiee ligand to resolve the changes that might have taken place during the complexation. The band at 1605 cm-'is characteristic of the azomethine group present in the fkee ligand. The lowering in this fiequency region (1588- 1560cm -l), observed in all the complexes, indicates the involvement of the azomethine nitrogen atom in coordination 85,86. The band at 1240cm-' is characteristic of the C-0 in the free ligand 'l. The shifting of this band to lower frequency region, observed in all the complexes, indicates 0-H group ionized and coordinated. The bands at 627-608 cm ' and 418-447cm -' are due to the formation of M-N and M-0 bonds respectively The presence of water in the above mentioned complexes is confirmed by the presence of weak band in the 931- 937 range which may be attributed " to bending vibration of water molecules in Mn (11), CO (II),Ni (11) and Cu (11) complexes. The other bending vibrations usually found at 1600cm-' which usually interferes with the skeleton vibration of benzene ring. The non-conducting nature and stochiometry of these complexes indicate that acetate is not present. 5. Electronic spectra The electronic spectra of all the complexes of H2DAP and H2DATP are recorded in DMSO. The important spectral bands of the complexes and their probable assignments are given in the Tables 1.4.3 and 1.4.6. In the present investigation Mn (11) complexes of H2DA.P and H2DATP show bands which corresponds to octahedral geometry 9'. The magnetic and other data also support octahedral geometry. In the present investigation Co(I1) complex of H2DAP shows absorptions at 560nm which can be assigned ( 4 ~ (F~) ,+ 4 ~ 2 g (F) ) in HzDAP and 473nm and 545nm in H2DATP ( 4 ~ l g ( ~ )4+~ 2 g ( ~ )()4, ~ l g (F)+ 4 ~ 2 g ( ~th)e) transitions of octahedral geometry. Low intensity of bands and purple color supports octahedral geometry color and other data also supports this observation 91. In the Ni (11) complex of H2DATP, absorption bands at 561and 972 nm and H2DAP complex bands at 564nm and 978 nm are assigned as given in the Table I. 4.3 and 1.4.6 . These data supports the octahedral geometry 96. In the case of copper (11) complexes of H2DATP and H2DAP absorption bands present at 678nrn and 690111x1 respectively are assigned '003'01 to the d-d transition in octahedral geometry. 6. Conclusion The complexes of Mn(I1) Co(II)), Ni(I1) Cu(I1) Zn(I1) and Cd(I1) with H2DAP and H2DATP are synthesized (H2L) .The physico chemical properties of all the complexes were studied . The octahedral complexes have the general formula [M (L ) (H20)2] where M= Mn (11) CO (11)), Ni (11) Cu (11) and L is tetra dentate dianion obtained fiom H2DAP and H2DATP) . The other tetrahedral complexes are assigned the formula [ML] where L is the tetra dentate dianionic ligand obtained fiom H2DAP and H2DATP where M= Cd (11). Zn (11) The IR data, conductance values and stoichiometry ofthe compound strongly proves this assumption . 7.Structure of ligands and complexes By considering the analytical data the structure of the ligand H2DAP and H2DATP and its Mn (II),Co(II), Ni(II),Cu(II),Zn(II) and Cd(I1) complexes are drawn . The proposed structure is given in Figures 1.4.1-1.4.6. Ligand- H2DAP Figure 1.4.1. Octahedral Complexes Figure 1.4.2. Complexes of H2DAP where M = Mn (II),Co,(II),Ni(II) and Cu(I1). Tetrahedral complexes Figure 1.4.3. Complexes of Hz DAP where M = Zn(II),Cd(II) Ligand -H2DATP Figure 1.4.4. Octahedral complexes. Figure 1.4.5. Complexes of HzDATP where M = Mn (II),Co,(II),Ni(II) and Cu(I1). Tetrahedral complexes. Figure 1.4.6. Complexes of H2DATP where M = Zn (11), Cd(I1) Table 1.4.1. Micro analytical, magnetic and conductance data of transition metal chelates of Dimedone bis -2-amino phenol ( H2DAP) Complexes found ( calculated) % Molecular Conductance Compounds Peff formula 0hm~'cm2mol BM Metal C H N HzDAP(Ligand) 73.6 6.6 8.1 C20H2202N2 (74.5) (6.83) (8.69) 13.32 58.2 [MnL(H20)2] mC20H2404N2 22 5.76 6.88 (13.36) (58.40) (5.84) (6.81) [CoL(H20)2] CoC20H2404N2 23 4'9 14.2 57.6 5.5 5.98 (14.19) (57.84) (5.78) (6.74) 14.5 56.98 5.77 6.66 H20)21 NiC~oH2404N~ 22 3'1 (14.15) (57.87) (5.78) (6.75) 16.2 57.1 5.01 6.01 (CuL(H20)2] C~C20H2404N2 32 (15 .14) (57.20) (5.72) (6.67) Zn 12 D 15.98 62.1 4.97 7.25 [ZnLI C20H2002N2 (16.96) (62.27) (5.1) (7.26) Cd D 24.8 55.4 3'92 6.40 [CdLl 16 C20H2002N2 (25.99) (55.50) (4'62) (6.47) Characteristic Infrared absorption frequencies (cm-')of transition metal chelates of HzDAP Compounds V (>C=N-) V (-C-0) y(-OH) V (M-N) V (M-0) Ligand H2DAP 1605s 1240m --- --m- --m- [MnL(H20)2] 1573m 1204m 937w 615w 447w [COL(HZO)~] 1588m 1194m 932m 609w 41 5w l3iL(H20)21 1580s 1232m 931w 627w 41 8w [CUL(H~O)Z] 1582s 1232m 933w 627m 41 8w [ZnLl 1560s 1234m --- 621m 41 8m [CdLl 1560s 1196w -- 608m 415m Strong = S, Medium= m, Weak=w broad =br Table. I. 4.3. Characteristic ultraviolet frequencies and probable assignment of transition with geometry of H2DAP complexes I I Complexes Band Assignment Geometry Octahedral Octahedral Octahedral Octahedral Tetrahedral Tetrahedral Table. I. 4.4. Micro analytical, of transition metal chelates of Dimedone bis aminothiophenol ( H2DATP) Complexes Conductance P Found (calculated)% eff 0hm~'cm2mol BM H2DATP (Ligand) C2oH22S2N2 D= diamagnetic Tab1e.I. 4.5. Characteristic Infrared absorption frequencies (cm-') of transition metal chelates of H2DATP Compounds U (>C=N-) U (-C-S) y .(-OH) U ( M-N) Ligand --- --- H2DATP 161O S 701m [MnL(H20)2] 1583s 690m 933m 41 8w [CoL(H20)2] 1584s 689m 935m 420m [NiL(H20)2] 1589s 686m 931 m 41 8m [CuL(H20)2] 1583s 694w 930m 418s [ZnLl 1582m 675w 937s 450w [CdLl 1589s 675w 932m 436w Strong = S, Medium= m, Weak=w broad =br Table. I. 4. 6. Characteristic ultraviolet frequencies And probable assignment of transition with geometry of H2DATP complexes Complexes Band nm Assignment Geometry [Mn L (H20)2] 389 CT Octahedral 473 [COL (H20)21 545 4 ~ l (gF ) + 4 ~ l (gP ) Octahedral 4 ~ g1( ~ -)+ 4 ~ 2 (gF ) [Ni L (H20121 56 1 3 ~ 2 g ( ~ ) - + 3 ~ l g ( ~ ) Octahedral 972 3 ~ 2 g ( ~ ) - + 3 ~ 2 ~ ( ~ ) [Cu L(H20)2] 678 2 ~ g - + ~ ~ 2 g Octahedral [ZnLl 420 CT Tetrahedral 529 [CdLl 432 CT Tetrahedral 3D sketches - - TifITWHEDRAL COMPLEXES OF H3tDAPIHzDAfP OCf- vO F &DkPIWATP Yellow = nydmjp; W- Csrtran: Blue= NYb.ogen; Cysn= oxrgBdsulphu Gray=m& CHAPTER 5 Studies on Mn(II),Co(II),Ni(II),Cu(II),Zn(II) and Cd(I1) Complexes of Cyclohexanone-2- Amino phenol(HCAP) and Cyclohexanone-2- Aminothiophenol (HCATP) The properties and reactivity of cyclic ketones attract a keen attention to several chemists. Numerous of their derivatives are biologically active compounds, some of which have found practical application. For example diketone derivatives are used in the synthesis of prostaglandins, antibiotics, and alkaloids. In addition, cyclic P-diketones are convenient model compounds for studying the effect of cyclic structure on the properties of the methylene and carbonyl groups and tautomeric equilibria 105-107 . The present study describes the synthesis of new bidentate Schiff base ligands developed fiom the cyclic ketone. Cyclohexanone-2- aminophenol(HCAP) and Cyclohexanone-2- aminothiophenol (HCATP) have been synthesized for the first time. These ligands produce various complexes with different transition metal ions. Literature survey reveals that no work has been done on the Schiff base complexes derived fiom the ligands HCAP and HCATP. Here HCAP can act as bi dentate anionic ligand containing the potential donor group ON while HCATP can also act as a bi dentate anionic ligand containing the SN donor group. It is highly scopefull to synthesize and characterize the complexes of HCAP and HCATP and to conduct detailed investigation about the structure, magnetic property, thermal stabilities, decomposition patterns and biological activities of these complexes. A . Experimental 1 . Materials and methods Detailed procedure and specification of reagents, which are useful for the characterization and purification of ligands are explained in chapter 11. 2. Preparations of ligands A hot ethanolic solution of cyclohexanone (0.Olmole) was added drop wise to a stirred solution of 2- arninophenol (.Olmole) dissolved in ethanol. The mixture was refluxed for about nearly 1 hour and then cooled. The pale pink precipitate formed was filtered , washed with alcohol then dried. Melting point is 121°C. To obtain HCATP the same procedure adopted for HCAP is used . Melting point is 134" C. 3. Synthesis of complexes The complexes were prepared by adding slowly a hot aqueous solution of the metal acetate to a refluxing ethanolic solution containing the ligand until the metal ligand ratio reached 1:2 .The reaction mixture was refluxed for 30' minutes and the complexes precipitated were separated. It was washed with water followed by ethanol, and dried over anhydrous Ca Ch. B. Results and discussions UV and IR ,NMR spectral data, magnetic studies, conductance measurements and the thermal data are used for the characterization of the ligands and the complexes. 1.Characterization of ligands TLC, CHN and IR data are used for establishing purity and homogeneity of ligands. 2. Formula and general properties of complexes All complexes are colored hygroscopic and stable they are soluble in DMSO. They are non-conducting in DMSO. The complexes were analyzed for metal by using atomic absorption spectroscopy and carbon , hydrogen and nitrogen estimated by standard micro analytic methods. The analytical data of the complexes corresponds to the formulae ML2 (H20)2 where M= Mn (11), CO (11), Ni (11), Cu (11), and ML2 where M=Zn (11) and Cd (11). Results are given the Table 1.5.1- 1.5.6. 3. Magnetic behavior Summary of the magnetic moments of the different metal complexes of HCAP and HCATP are given in the Table. 1.5.1 and 1.5.4. In the case of Mn (11) complexes of HCAP and HCATP the magnetic moment values are about 6.02 and 5.98 which show an octahedral geometry l 9 . The cobalt (11) complexes possess magnetic moment values of 5.19 and 5.06 BM as for octahedral geometry. The complexes of Ni have magnetic moment value 3.1 BM for HCAP and 3.2 BM for HCATP which are in with octahedral complexes. The magnetic moment values of Cu (11) are 2.0 BM and 1.86 B.M as expected2' for octahedral geometry. The reference and the method for theoretical prediction are already explained in the chapter I11 .The Zn(I1) and Cd(I1) complexes are found to be diamagnetic 4. IR spectra The ligand HCATP shows bands at 1579 cm -' and 2655 cm -' which are due to C=N stretching and S-H stretching'04 respectively. The band at 698 cm -' is probably due to C-S streching'04 . The IR spectra of the complexes are compared with that of the free ligand to assign the changes that might have taken place during the complexation. The band at 1579 cm-' is characteristic of the azomethine nitrogen atom present in the free ligand. The lowering of bands to the frequency region (1 572 - 1560 cm -l ), observed in all the complexes, indicates the involvement of the azomethine nitrogen atom in coordination 85,86 . The band at 698cm-'is characteristic of the C-S in the free ligand. The shifling of this frequency region, observed in all the complexes, indicates that S-H group is ionized and CO-coordinate5d1 ,104 . The bands at 41 8 cm -l -436 cm -l are due to the formation of M-N bonds. In the case of complexes of Mn(I1) ,Ni(II) ,Co(II) and Cu (11) the presence of OH fiequency at 922 cm -' - 936 cm -' further confirms 51,104 the presence of coordinated water. The characteristic frequency of fiee acetate ion at 1560 cm -' and 1415 cm -' are absent in all the complexes but the non-conducting nature and stoichiometry of this complex indicate that acetate ion is not present. IR spectra HCAP shows bands at 1605 cm -l and 3450 cm -l which are due to C=N stretching and 0-H stretching respectively. The band at 1226 cm -' is probably due to C-0 stretching. The IR spectra of the complexes are compared with that of the fiee ligand to determine the changes that might have taken place during the complexation. The band at 1605 cm-' is characteristic of the azomethine nitrogen atom present in the free ligand. The lowering of this band to the region (1599 - 1565cm -l ), observed in all the complexes, indicates the involvement of the azomethine nitrogen atom in coordination 85986 . The band at 1226cm-'is characteristic of the C-0 in the free ligand. The shifting of this frequency region, observed in all the complexes, indicates 0-H group is ionized and coordinated. The bands at 523-506 cm -l and 432- cm-' - 41 8cm-' which are due to the formation of M-N and M 4 b onds respectively.8478I8n the case of CO (W, Mn(II),Ni (II),Cu (11) the presence of OH frequency at 93 1 cm -' -935 cm -l further confirms 51,104 the presence of coordinated water. The non-conducting nature and stochiometry of this complex indicate that acetate ion is not present. 5) Electronic spectra The electronic spectra of all the complexes of HCAP and HCATP are recorded in DMSO The important spectral bands of the complexes and their probable assignments are given in the Table, 1.5.3, 1.5.6. In the present investigation Mn (11) complex of HCAP and HCATP shows weak bands at 401 nm, 420 nm may be due to charge transfer spectra. Pale pink color also proves the existence of octahedral geometry 91. Co(I1) complex of HCATP shows absorptions which can be assigned to the ' T I ~ F-)+ 'A~,(F) transition of octahedral geometry as given in the Table . Low intensity of bands supports octahedral geometry. HCAP complexes of CO (11) shows absorptions which can be assigned to 'T~~(F)+' A~~(F)',T I~(F)+ 4 T2g(F) transitions of octahedral geometry low intensity of bands supports octahedral geometry. Ni (11) complex of HCAP shows bands at 634 nrn and 1010nm ,that of HCATP shows bands at 1152nm and 548nm which are assigned to octahedral stereochemistry 96 as given in the Table. Cu (11) complexes of HCAP and HCATP show absorption bands at 576nm and 636111x1 which assigned to the d-d transition in octahedral geometry 100,101 ,with transition 2To the color of the complex also supports this geometry . 6.NMR spectra In the case of H2 CAP, complexes, the proton NMR spectra of diamagnetic i * complexes were compared with free ligand. The OH singlets 1 1.1 and 10.1 which * S v d U is present in the tkee ligand disappears in Zn (11) and Cd (11) complexes. The above results clearly indicating the participation of the OH group in chelation 5' . Similarly, in the case of H2 CATP complexes, the proton NMR spectra of Ir Z diamagnetic complexes were compared with fiee ligand. The SH singlets 3.1 and 3.8 which is present in the fiee ligand disappears in Zn (11) and Cd (11) complexes , which indicate that SH proton is removed by chelation. 51 7. Conclusion The coordination compounds of Cu (11) , Mn (11) ,N i(I1) , Co(I1) ,Zn (11) and Cd(I1) with HCAP and HCATP are synthesized The physico chemical properties of all the complexes were studied . The complexes have the general formula [M(L)2(H20)2] where M= Mn(I1) Co(I1)) Ni(I1) Cu(I1) and HL =HCAP or HCATP. The other complexes have been assigned the formula [ML*] where M=, Zn (11) or Cd(I1) and HL =HCAP, HCATP. 8.Structure of Ligands and complexes By considering the analytical data the structure of the ligand HCAP and HCATP and its Mn(II),Co(II), Ni(II),Cu(II),Zn(II),Cd(II) are drawn . The proposed structure is given in Fig 1.5.1-1.5.6. Ligand- HCAP Figure 1.5.1 Octahedral Complexes Figure 1.5.2 Complexes of HCAP where M = Mn(II),Co,(II),Ni(II) and Cu(I1). Tetrahedral complexes Figure 1.5.3 Complexes of HCAP where M = Zn (II),Cd(II) Ligand -HCATP Figure 1.5.4 Octahedral complexes Figure 1.5.5 Complexes of HCATP where M = Mn (II),Co,(II),Ni(II) and Cu(I1). Tetrahedral complexes Figure 1.5.6 Complexes of HCATP where M = Zn (11) and Cd(I1) Table I. 5.1 Micro analytical, magnetic and Conductance data of transition metal chelates of Cyclohexanone-2- amino phenol ( HCAP) complexes l Conductance Molecular Found (calculated)% Compound P eff formula O h - BM 'cm2mol-' Metal C H N HCAP(Ligand) 75.8 7.01 Ci2HisON 7.29 (76.2) (7.9) (7.40) - 13 "02 11.1 61.00 6.3 5.82 [MnL2 (H20121 mC24H3204N2 (1 1.76) (61.67) (6.85) (5.99) iCoL2 (H20)21 CoC24H3204N2 11 "l9 12.4 61.3 6.1 5.2 (12.50) (61.15) (6.79) (5.94) 21 3.' 12.6 61.08 6.02 5.09 [NiL2 (H20)2] NiC24H3204N2 (12.47) (61.18) (6.79) (5.94) 12.4 60.1 5.9 5.1 1 [ C u b (H20)21 C~C24H3204N2 13 (13.36) (60.56) (6.72) (5.88) D 14.2 64.9 5.99 6.3 [ZnLzI Zn C24H2802N2 12 (14.80) (65.24) (6.34) (6.34) l Cd 22.9 58.2 5.77 5.70 [CdL21 13 D C24H2802N2 (23.01) (58.96) (5.73) (5.73) D=diamagnetic Table 1.5.2 Characteristic Infrared absorption frequencies (cm")of the of HCAP complexes Compounds Y -OH 2) (>c=N-) (H20) 'U (M- N) 'U (M-0) Ligand 1605s 1226m ---- ---- ---- [MnL2 (H20121 1584s 1203m 931 m 517 m 418 w [CoL2 (H20121 1599s 1221m 931 m 507m 41 8w [NiL2 (H20)2] 1565m 1 198m 934m 506w 432w [CULZ(H 20)2] 1599s 1211m 935m 523w 41 8w [znL21 1565s 1128m 523w 423w [CdL21 1587s 1203m 51 9w 420w Strong = S, Medium= m, Weak=w broad =br Table 1.5.3 Characteristic ultraviolet frequencies And probable assignment of transition with geometry of HCAP complexes Complex Band nm Assignment Geometry [MnL2 (H20)2] 40 1 CT Octahedral 544 [CoL2 (H20)21 4~ l gm-, 4 ~ 2 g ( ~ ) 1079 Octahedral 4 ~ l g ( ~ )4- ~+ 2 g ( ~ ) 634 Octahedral (H20121 1010 'A~!(F) --r3'rlg(~) ~ ~ g - * ~ ~ ~ g 2 Octahedral [CuL2 (H20121 576 Eg- 2 ~ 2 g [znL21 420 CT Tetrahedral 360 CT [CdL2] 529 Tetrahedral Table I. 5.4 Micro analytical, data of transition metal chelates of Cyclohexanone-2- aminothaiophenol ( HCATP) complexes Conductance Found (calculated)% Compound Molecular formula P eff ohm-'cm2mol-' BM Metal C H N HCATP (Ligand) 69.8 7.1 6.2 Ci2Hi5SN (70.24) (7.31) (6.82) 10.7 56.89 6.2 5.1 [ M n b ( H20)2] mC24H32S202N2 13 5'g8 (11.01) (57.72) (6.41) (5.6) 11 "06 11.0 58.1 6.31 5.57 [CoL2 (H20)2] CO C ~ ~ H ~ ~ S Z O Z N ~ (11 .71) (57.26) (6.36) (5.56) 21 3'20 11.62 57.08 6.32 5.34 [Nib (H20)21 Ni C24H32S202N2 (11.67) (57.29) (6.36) (5.56) (H20)21 Cu C24H32S202N2 13 12.11 56.1 6.1 5.05 (12.52) (56.74) (6.30) (5.51) 13.2 59.7 5.99 5.6 [ZnL2] Zn C24H28S2N2 12 D (13.81) (60.83) (5.91) (5.91) 21.0 55.0 6.01 5.98 [CdLz] Cd H24H28S2N~ 18 D (21.59) (55.34) (5.38) (5.38) D= diamagnetic Table 1.5.5 Characteristic Infrared absorption frequencies (cm-') of transition metal chelates of HCATP Compounds U (M-N) [znL21 15 64 [CdL2] 1569s Strong = S, Medium= m, We ;=W broad : Table I. 5.6 Characteristic ultraviolet frequencies And probable assignment of transition with geometry of HCATP complexes Band Complex Assignment Geometry (nm) CT (H20)2] 420 Octahedral COL^ 570 4 ~ l(Fg) + 4 ~ 2 g(F ) (H20)2] Octahedral 1152 3 ~ 2 (gF ) + 3 ~ 2 g (F) Octahedral (H20121 548 3 ~ 2 (gF) - t3,~(F ), [CuL2 (H20121 636 2 Eg-t2T2, Octahedral [znL21 336 CT Tetrahedral CT [CdL21 345 Tetrahedral CHAPTER 6 Studies on Mn (11), CO( 11), Ni (II), Cu (11), Zn (11) and Cd (11) Complexes of Pyrolidone-2- aminophenol (HPAP) and Pyrolidone -2-aminothiophenol (HPATP) Two bidentate Schiff base ligands pyrolidone-2- aminophenol (HPAP) and pyrolidone -2-aminthiophenol (HPATP) have been synthesized for the first time. These ligands produce various complexes with different transition metal ions. Studies show that no work has been done on the complexes of pyrolidone and aminophenol or arninothiophenol. Here HPAP can act as a bidentate ligand containing the ON donor group while. HPATP, can act as a bidentate ligand containing the SN donor group. So it is interesting to synthesize and characterize the complexes of HPAP and HPATP and to conduct detailed investigation about structure, magnetic property, thermal stabilities, decomposition patterns and biological activities of these complexes . A. Experimental 1) Materials and methods Details regarding the reagents used, procedure adopted for the characterization of the ligand and complexes are given in chapter 11. 2) Preparations of ligands A hot ethanolic solution of pyrolidone (O.Olmo1) was added drop wise to a stirred solution (.Olmol) of 2 aminophenol dissolved in ethanol . The mixture was refluxed for about 20 minutes and then cooled. The precipitate formed was filtered, washed with alcohol and then dried. Melting point is 1 3 8 ' ~ yield 91% . To obtain HPATP the same procedure is used for synthesizing the ligand HPAP adopted. Melting point. 151°c . Yield 87%. 3) Synthesis of complexes The complexes were prepared by adding slowly a hot aqueous solution of the metal acetate to a refluxing ethanolic solution of the ligand until the metal ligand ratio reached 1:2. The reaction mixture was refluxed for 20 minutes and the complexes precipitated were separated. It was washed with water followed by ethanol and dried over anhydrous Ca Cl2. B. Results and discussions The complexes were characterized on the basis of elemental analysis ,UV ,IR spectral data, magnetic studies, conductance measurements and the thermal data as given in the Tables ;1 .6.1- 1.6.6. 1,Characterization of ligands The ligands were characterized using TLC,CI-IN and IR spectral data .The assigned structure for the ligands are given in the figures ;1 .6.1 and 1.6.4. 2. Formula and general properties of complexes All the complexes are colored, photostable and non hygroscopic. They have low solubility in organic solvents but high solubility in DMF and DMSO.The values of electrical conductivity of the complexes in DMSO show that they are non-electrolytic compounds. The complexes were analyzed for metal, carbon, hydrogen, and nitrogen, by atomic absorption spectroscopy and standard micro analytical methods. Results are given in the Tables ; 1.6.1- 1.6.6. 3. Magnetic behavior In the case of HPAP and HPATP complexes of Mn (11) the observed magnetic moment values are 5.96 BM and 5.89 BM which proves the existence of octahedral geometry. The CO (11) complexes of HPAP and HPATP possess magnetic moment values of 4.8 and 4.9 BM as expected for octahedral geometry. The complexes of Ni (11) have magnetic moment values 3.01BM and 3.1 BM which are in accordance with octahedral complexes. The magnetic moment values of Cu(I1) complexes possess normal values of 1.92 and 1.82 B.M as expected for octahedral geometry. The Zn (11) and Cd(I1) complexes are found to be diamagnetic. 4.IR spectra HPATP complexes shows band at a 1616 cm-'. This is due to C=N stretching. The lowering of this fiequency region (1597 cm-' - 1565 cm-'), observed in all the complexes, indicates the involvement of the azomethine nitrogen atom in coordination The band at 692cm-'is characteristic of the C-S in the free ligand. The shifting of this fiequency region, observed in all the complexes, indicates that S-H group is ionized and CO-coordinated.T he bands at 418-430 cm-' which are due to the formation of M-N bonds. Presence of a broad band around 3200 cm-' (except in Zn (11), Cd (11)) may be due to the OH stretching of coordinated water, which further confirmed from -OH bending frequencies . In the case of HPAP the band at 1605 cm-l in fiee ligand is due to the presence of azomethane linkage in fiee ligand. During the complexation this value is changing into 1598- 1564cm-' .The C-0 band in the fiee ligand is 1226 which is changing to 1138-11 94 cm" in complexes which indicate the participation of phenolic group in the complexation. The bands at 596-536cm-' which are due to M-N bonds and the bands 412-478cm-'indicate M-0 bonds. The bands around 3 2 0 0 ~p~ro'v es the presence coordinated water which is further confirmed by bands near 930cm-' except in Zn(II), Cd(II).The characteristic frequency of fkee acetate ion at 1560 cm",1415 cm" are absent in all the complexes but the non- conducting nature and stoichiometry of this complexes indicate that acetate ion is not present . 5. Electronic spectra The electronic spectra of all the complexes of HPAP and HPATP are recorded in DMSO. The important spectral bands of the complexes and their probable assignments are given in Tables. 1.6.3 and 1.6.6. In the present investigation Mn (11) complex of HPAP and HPATP shows the band appearing below 400nm only which are due to CT bands. The electronic spectrum of CO (11) complex of the ligand HPAP gives two characteristic bands at 442 and 55 lnm respectively. In the case of Ligand HPATP characteristic band at 452 and 561nm. In both cases the characteristic bands prove the octahedral geometry . Ni (11) complex shows bands at 564nm and 978nm in HPAP and 551 in HPAP assigned as given in the Tables 1.6.3 and 1.6.6 . Experimentally obtained data supports the octahedral geometry. Color also supports this observation. In the present investigation Co(I1) complex shows absorptions which can be assigned to the d-d transitions of octahedral geometry. Low intensity of bands and purple color supports octahedral geometry. In the case of Cu (11) complexes, absorption maximum at about 666 nm and 732nm supports octahedral geometry. The available data of Zn (II),Cd (11) are insufficient predict the geometry of complexes but as they are four coordinated so tetrahedral geometry is the preferred structure for both complexes . 6.NMR spectra In the case of H2 PAP, complexes, the proton NMR spectra of diamagnetic complexes [(Zn (PAP)2] and [Cd (PAP)2] were compared with fiee ligand. The OH singlet 10 .1 ppm and 10 .9 ppm which is present in the fiee ligand disappears in Zn (11) and Cd (11) complexes. The above results clearly indicating the participation of the OH group in chelation 'l. in the case of H2 CATP complexes, The SH singlets 3.lppm and 3.0 ppm which is present in the free ligand disappears in Zn (11) and Cd (11) complexes , which indicate that S13 proton is removed by chelation. '' 7. Conclusion. Mn (11), CO (11), Ni(II), Cu(II), Zn(I1) and Cd(I1) complexes of HPAP and HPATP were synthesized . The physico chemical properties of all the complexes were studied. The complexes have the general formula [M(L)2(H20)2] where M= Mn(II),Co (II),Ni (11) and Cu (11)) and L is bi dentate anion obtained from HPAP or HPATP .For the other complexes is the formula [ML2] is assigned where L is the bi dentate anionic ligand obtained fiom HPAP or HPATP where M=Zn (1I)or Cd(I1). The IR data, NMR , conductance values and stochiometry of the compounds strongly proves this assumption. The data obtained are insufficient to prescribe the exact geometry of Zn(I1) and Cd(I1) . However in comparison with structure of other complexes and considering common coordination numbers exhibited by these metal ions, a four coordinated tetrahedral geometry may be assigned to them. 8.Structure of ligands and complexes By considering the analytical data the structure of the ligand, Mn (II),Co (11), Ni (II),Cu (II),Zn (11) and Cd (11) complexes are drawn . The proposed structures are given in Figure 1.6.1- 1.6.3. Ligand- IIPAP Figure 1.6.1 Octahedral Complexes OH2 Figure 1.6.2 Complexes of HPAP where M = Mn (II),Co,(II),Ni (11) and Cu(I1). Tetrahedral complexes Figure 1.6.3 Complexes of HPAP where M = Zn (II),Cd (11) Ligand -HPATP H SH Figure 1.6.4 Octahedral complexes Figure 1.6.5 Complexes of HPATP where M = Mn (II),Co,(II),Ni(II) and Cu(I1). Tetrahedral complexes Figure 1.6.6 Complexes of HPATP where M = Zn (11), Cd(I1) Table I. 6.1 Micro analytical, Magnetic and Conductance data of transition metal chelates of pyrolidone -2-aminophenol (HPAP) complexes Table I. 6.2 Characteristic Infrared absorption frequencies (cm-')of Transition metal chelates of HPAP Substance 2) (OH ) 2) 2) ~ ( 0 - H ) 2) 'U (H20) (>C=N-) (-C-0) (H201 (M-N) (M-0) HPAP -1igand -- 1605s 1226m ---- ----- ------ [MnL2 {H20)12 3246b 1587m 11 72m 934m 544w 459m [COL2 H201 3251 b 1597m 1 138m 932m 540w 447w {H20I2] 3222b 15 64m 1 194m 976m 563w 478w [CuL2 H201 3210b 1598s 1 196m 935m 596w 529m [ZnL2] -- 1592s 1 19 0m --- 534w 436m [CdL2] -- 1578s 1 194m --- 536w 412w Strong = S, Medium= m, Weak=w broad =b Table 1.6. 3 Characteristic ultraviolet frequencies and probable assignment of transition with geometry of HPAP complexes Complex Band nrn Assignment Geometry [MnL2 (H20)2] 371 CT Octahedral 442 4 ~ l g ( ~ )4+~ l g ( ~ ) [COL( H20121 551 4 ~ l g ( ~ )4+~ 2 g ( ~ ) Octahedral [NiL{H20]2] 564 3 +2g+3 T 1g (F) Octahedral 978 Azg+3T2g [CUL~(H~O)~] 666 2 E P 2 T 2 g Octahedral [ZnLz] 420 CT Tetrahedral 360 CT [CdL2] Tetrahedral Table I. 6.4 Micro analytical, magnetic and Conductance data of transition metal chelates of Pyrolidone-2- aminothiophenol (HPATP) Complexes ~ o u n d(c alculated)% Molecular Compound Peff formula Conductance BM ohm-'cm2mol-' Metal C H N - 61'8 5'9 13.9 HPATP C10H12N2S m--- -- (62.5) (6.25) (14.58) [MnL2 5.89 10.6 50.3 5.22 11.0 mC2oH2602S2N4 12 (H20)21 (11 .61) (50.74) (5.49) (11 .84) 12.3 50.34 4.97 11.2 [C0L2(H20)2] C O C ~ O H ~ ~ O ~ S ~8N.0 ~ 4'9 (12.35) (50.32) (5.46) (11.74) 11.8 49.9 5.5 11.8 [NiL2(H20)2] NiC20H2602S~N4 9.0 (12.31) (50.34) (5.45) (11.74) 13.01 49.7 5.32 11.06 [C~L2(H20)2] C U C ~ O H ~ ~ O ~ S ~1N2 ~ l'" ( l3 .19) (49.83) (5.39) (11 .62) 14.06 54.2 4.90 12.5 [ZnLzI ~ n ~ 2 0 ~ 2 2 ~ 2 ~ 411 D (14.61) (53.64) (4.91) (12.51) 22.3 48.2 4.32 11.4 [C&] CdC20H22S2N4 14 D (22.73) (48.54) (4.44) (11 .32) Table I. 6.5. Characteristic Infrared absorption frequencies (cm-')of transition metal chelates of HPATP Substance U OH U ('C=N-) Y OH (1320) U ( C-S) U (M-N) HPATP -1igand ---- 1616 s --- 692m -- 679m [MnL2(H20)2] 3250b 1597s 925w 430w [CoL2 (H20)2] 3249b 1583s 923w 696w 444w [NiL2(H20)2] 324b 1597s 943w 688w 41 8w [CUL~(H~O)~] 322b 1565s 921w 619w 418w [ZnL21 ---- 1585m --- 676w 430w [CdL2] --- 1569s --- 687w 462w Strong = S, Medium= m, Weak=w broad =b Table I. 6.6 Characteristic ultraviolet frequencies and probable assignment of transition vvith geometry of HPATP complexes Band Complex nm Assignment Geometry CT 360 [MnL2 (H20121 Octahedral 387 , + 4 ~ 2 g ( ~ ) 482 4 ~ 1 g ( ~ )4+~ 1 g ( ~ ) [COL~(H~O)~] 56 1 4 ~ l g ( ~ 4) +~ 2 g ( ~ ) Octahedral [NiL2 (H20121 551 3A28+3Tlg(F) Octahedral 2 [C~L2(H20)2] 732 ~ g + ~ ~ 2 g Octahedral [znL21 565 CT Tetrahedral [CdL2] 420 CT Tetrahedral . 2 4 ( P y r o I i d h - 2 - W W i t ~ ] P h dH PAP . 2~dldln-2-Wdenadmim]Ben~on~tHhPi~AIT P OCTAHEDRAL COMPLEXES OF HPAPIMFATP Yelkvv 3 Hydrogen; ked = Carbon; M - Wmgm; Cyiima aygent sNhur *- Gmy=msOel T h s 3 0 s ~ ~ m d n a m i y l ~ d m b a e ~ t t t e o n U r s d ~ d A C D s d t w m w Wh oi wdsr lo n Jownsl ofAmHmtn C h e W S mkty and the s t ~ d the hmdacu~ler, is on ly an appdmablon 93 REFERENCES 1) Karn0,N.G.; Ratnasamy, S.; Patrick J. 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San Francisco. 1962 105) Russian Journal of General Chemistry, Vol. 72, No. 8, 2002, Translated from Zhurnal Obshchei Khimii, 2002 , 1320-1324. 106) Akhrem, A.A., Lakhvich, F.A., Pshenichnyi, V.N.; Lakhvich, O.F. Dokl. Akad. Nauk SSSR. 1978,240,3. 107) Ismail, K.A.; El- Tombary, A.A.; Aboulwafa, O.M.; Omar A-Mohsen. M.E.; El- Rewini, S.H. Arch.Pharri~.1 996, 329, 10, 437. PART II THERMO GRAVIMETRIC ANALYSIS OF SCHIFF BASE COMPLEXES Abdul Jaleel.U.C “Synthesis, thermal and spectral studies of some transition metal complexes of schiff bases” Thesis. Department of Chemistry , University of Calicut, 2005 Part I1 THERM0 GRAVIMETRIC ANALYSIS SCHIFF BASE COMPLEXES OF Cu (11), Ni (11) AND Zn (11) Among the different analytical methods the thermal studies possess significant use in the structural and kinetic studies of coordination compounds. This analytical method is composed of different techniques such as thermogravimetry (TG), differential thermal analysis (DTA), derivative thermo gravimetry (DTG) and differential scanning calorirnetery (DSc). Thermogravimetry is one of the oldest thermo analytical procedures and has been used extensively in different fields of science It also has wide application in the structural studies of coordination compounds. 36. The technique involves monitoring the weight loss of the sample in a chosen atmosphere (usually nitrogen or air) as a fbnction of temperature. The resulting mass change versus temperature curve provides information concerning the thermal stability and composition of the initial sample. The analytical instrument used is a thermo balance with a furnace programmed for a linear rise of temperature with time.' The derivative thermo gravimetric curve may be obtained either by manual differentiation of the normal thermo gravimetric curve or by suitable instrumentation. It gives the relation ship between the rate of weight change and the temperature .DTG curves have a number of peaks instead of steps . In these curves , the area under the peaks is proportional to the total change in weight .The usefulness of TGA for analysing complexes was greatly enhanced by the introduction of the ability to record simultaneously the first derivative of the weight loss. This is referred to as derivative thermo gravimetric analysis (DTG).~,~ TG is inherently quantitative and therefore an extremely powerful thermal technique, the ability to analyse the volatile products during a weight loss is of great value. The ability of TG to generate fhdamental quantitative data fiom almost any class of materials has led to its widespread use in every field of science and technology.7 . Many factors influence the form of the TG curve, both sample and instrument related some of which are interactive. The primary factors are heating rate and sample size, an increase in either of which tends to increase the temperature at which sample decomposition occurs and to decrease the resolution between successive mass losses. The particle size of the sample material, the way in which it is packed, the crucible shape and the gas flow rate can also affect the progress of the reaction. Careful attention to consistency in experimental details normally results in good reproducibility. On the other hand studying the effect of deliberate alterations in such factors as the heating rate can give valuable insights into the nature of the observed rea~tions.~ Key application areas of different thermal analysis can be summarized as l given below. I Thermal Stability: Related materials can be compared at elevated temperatures under the required atmosphere. The TG curve can help to elucidate decomposition mechanisms. Kinetic Studies: A variety of methods exist for analysing the kinetic features of all types of weight loss or gain either with a view to predictive studies or to understanding the mechanisms in chemistry. Material characterization: TG and DTA curves can be used to "fingerprint" materials for identification or quality control. It has obvious uses in the determination of the moisture content of powders, water of hydration and of carbon monoxide and carbon dioxide evolution fiom carbonates etc. In Inorganic chemistry the technique has been widely used to study the kinetic and thermal behavior of coordination compounds. The valuable information given by thermo gravirnetric analysis of coordination compound includes . a) Temperature regions of stability b) Temperature of inception of maximum rate c) Temperature of the completion of decomposition On the other hand DTA gives the information like enthalpy changes during the decomposition. The following authors give much insight to the technical and theoretical aspects of thermal analysis. l) ~ r o w n ~2), ~ u v a l, ~3) chiang9, 4) ~arn'', 6) ~chulzel ,l 7) wendlandt12. Thermogravimetry, differential thermal analysis and other thermo analytical methods can be used to study the kinetics of a chemical reaction and to determine the basic kinetic constants such as the rate constant, activation energy, order of the reaction and frequency factor. These methods usually measure continuously and automatically a change in some physical properties such as weight enthalpy, length or volume of the given system as a function of temperature . Kinetic analysis In kinetic studies which is based on the observation of weight change, two approaches are possible Isothermal( static) and Non isothermal (dynamic heating) Non isothermal (dynamic heating) The non-isothermal method is the determination of the degree of transformation as a fbnction of time during a linear increase of temperature compared with static method . The hndamental calculation of kinetic data from a TG curve is based on the kinetic equation -dx/dt =kxn (1) here x is the amount of the sample undergoing reaction, n is the order of the reaction and k is the specific rate constant. The temperature dependence of the specific rate constant k is expressed by Arrhenius equation k=A e-EmT (2) where A is the pre exponential factor , E is the activation energy, R is the universal gas constant and T is the absolute temperature lI Consider a solid state reaction of the kind A (solid) +B (solid) + C (gas) I For monitoring the above reaction from mass loss , a dimension less quantity, the fractional decomposition a which at time t is defined as the fraction of A the sample decomposed, is employed . The relation ship of X to mass loss W is given by the equation. dx = m. dwlwa (3) Where m, is the initial mass of the sample, and W, is the maximum mass loss .By integrating the equation with left hand side limit of m, to X and right hand side limit of zero to W ,f ollowing equation will be obtained X =mo (W,-W)w/ a (4) By substituting equation (4) and (2) in equation (1) and by differentiating the logarithmic form, an expression is obtained which is used in the differential method. Integral method is using the integrated form of the equation ( l ) after the transposition of the mass loss W, in equation (3), (4) The mathematical treatments of kinetic equation make use of one of the following three methods of evaluation 1 Differential methods 2 Integral methods 3 Approximation methods Using these approaches number of equations are derived by different authors. 13-15 only one integral method used in the present study and outlined in this chapter. Coats Redfern method14 Integral methods are generally accepted as the most precise among the methods accessible for the determination of kinetic parameters from TG data The disadvantages are prior determination of 'n' is required and temperature integral has to be approximated in this method. Consider that in the reaction aA+bB+C (g) The rate of disappearance of A decomposed at a time t is give n by daldt=k(l-a)" Where n is the order of reaction and k is the rate constant By combining equations (2) and (5) rearranging and integrating at constant heating rate Q= dT/dt we obtain ojEd d(1-a ) '= A/@oj"exp (-EIRT) dT (6) The left hand side of this equation has two different solutions depending on the value of n namely 1-(1- a) ' -" / ( l -n )f~or~ n =/l (7) and -log(l- a)/T2 for n=l In both cases the right hand side of equation has the solution AR/@E(l-2RTIE)e xp (-EIRT) The following two equations are obtained after taking logarithms In [l-(1- a) ' -" l ( l -n )f~or~ = In[AW@E(l-2RT/E]-EIRT n=/l (10) And In(-log(1- a ) l ~ ~ =[lAnR /@E(l-2Rt/E]-EIRTf or n=l (11) In ordinary thermal decomposition reactions In [ARI@E(l-2Rt/E] is practically constant and plots of In [l-(1- a) ' -" / ( l -n )~v~s . l/T for n =/l .ln(l-(l- a)/T2v s. 1/T for n=l respectively result in straight line with slope of -E/2.303R for correctly chosen value of 'n'. Using this value of n the kinetic parameters were calculated . The entropy of activation was obtained from the equation A= kTsh exp(-' Where k =Boltzman constant h=Planks constant Ts=Peak temperature The activation entropy, the activation enthalpy and the fiee energy of activation were calculated using the following equations AS =2.303[log (Ah/kt)] R (AH:), (AG:), A H ~=,E X -RT 16,17 AG%=AH%-TAS1%6J7 Where k and h are the Boltzman constant and Plank constant respectively . Scope of present investigation In this part the results of kinetic decompositions of Cu (11), Ni (1I)and Zn(II)complexes of H2DAP, H2DSC, H2DATP using TG are presented. From the TG curves the temperature regions of stability have been noted. The temperature of inception and decomposition and temperature of maximum rate of decomposition have been noted. The thermal stability and decomposition stages of the complexes have been noted . The non-isothermal TG curves have been subjected to mathematical analysis using the integral methods of Coats Redfern and the activation parameters have been evaluated for all the complexes . Chapter 2 THERMAL DECOMPOSITION KINETICS OF Ni (11), Cu (11) and Zn (11) COMPLEXES OF DIMEDONE BIS SEMICARBAZONE Several attempts were made to study the thermal behavior of the complexes containing azomethine linkage1 8 -22 . The early papers which give much insight to this area of study was by Wendlandt eta12 4-26 . The thermal studies of these complexes give information about the coordinated water molecules, thermal stability and the coordination number. Schemes of thermal decomposition of the complexes have also been proposed ". In the recent papers the determination of enthalpy of activation and fiee energy of activation have also been made 16. In this chapter thermo gravimetric analysis (both TG and DTG) of some Schiff base coordination compounds are described in detail. TG and DTG techniques are helpful in establishing the structure of coordination compounds and the studying of kinetics of their decomposition. Coats Red fern equation14 was applied. The kinetic and thermodynamic parameters like fiequency factor (A), order of the reaction (n), activation energy (E), enthalpy of activation ( ~ ~ $ ) , e n torfo a~cti~va tion(AS 3 and fiee energy of ac t iva t ion , (~~w~e)r e evaluated16. Here studies of the thermal decomposition of three representative complexes viz dimedone bis semicarbazone (H2DSC) of Cu (11) Ni (11) and Zn (11) are described. In this chapter interpretation and mathematical analysis of these thermal decomposition data and evaluation of the order of the reaction, fiee energy and entropy of activation, enthalpy of activation and pre exponential factor based on the Coats Red fern equation are also described . Experimental Preparative procedures for the ligand and the complexes were described in part 1. Thermo gravimetric and differential thermal analysis curves are traced in an atmosphere of the static air at a constant heating rate of 10~~rnin-laan dsa mple of 2- 5mg were used for the study. Kinetic and thermo dynamical parameters were calculated by using Coats Red fern equation with a personal system using a Microsoft Excel work sheet . Treatment of data The instrumental TG and DTA curves were redrawn using Microsoft Excel worksheet. It is represented in the Fig No.II.2.1--11.2.3. By using Coats Redfern equation the kinetic and thermodynamic parameters for the metal chelates were calculated. The corresponding values of E, A, AH~A, G:, AS: are given in the Table I1 .2.1-11.2.6 . Results and discussion Thermal decomposition curve of the [CuL (H20) 2] gives a three-stage decomposition pattern which is supported by the DTG data. The first stage represents loss of 2H20 molecules According to Nikolaev et a1 27 water eliminated around 150 'C can be considered as coordinated water. The second stage represents the loss of dirnedone part and 1 semicarbazone part. In the third stage another semicarbazone moiety is disappearing. The over all stepwise reaction can be represented CuL (H20) 80-180°C 2 dehydration CuL CUL pertial demmposition + 180-3800C intermediates Intermediates 380-560°C fimr decomposition -+ metal oxides DTG curve gives well-defined peaks in the appropriate region. The over all loss of mass fiom the curve is 77.5%while the theoretical loss in mass during the decomposition of the complex is 77.81. The data obtained are given in the Tables.II.2. land 11.2.2. The negative values of (AS $) for most of the complexes means that the activated complex is more ordered than the reactant and that the reactions are slow. The more ordered nature might be due to polarization of bonds in the activation state, which might happen through charge transfer electronic transition^.^ In the case of Ni (11) chelate a three stage decomposition pattern is observed. First decomposition stage in this case is about 9.4 %. It is quite reasonable to assume that it is due to loss of 2 water molecule. The peak temperature is about 120 'C . The second stage is a partial decomposition due to the loss of 2 semicarbazone part . Third stage is the final decomposition and subsequent formation of corresponding oxide NiL(H20)2 80-160°C N ~ L dehydration * NiL 160-340°C partial decomposition + intermediates Intermediates final decomposition -) 340"400C metal oxides The total mass loss 78% is obtained for this decomposition. This value is in accordance with theoretical loss percentage and pyrolysis data given in the Table 11.2.3 The kinetic and thermodynamic parameters calculated by using Coats Redfern equation summarized in the Table 11.2.4. The Zn (11) chelate showed a two-stage decomposition pattern. The first stage is loss of dimedone part and I molecule of the semicarbazone part. Second stage decomposition is due to the loss of semicarbazone moiety. At the end of the stage total mass loss is found to be 74.9%, which is very close to the theoretical value and pyrolytic data. 160-300oC partial decomposition intermediates Intennediate~ 300450oC fiml decomposition + metal oxides The activation energies obtained for the main decomposition stage of these three complexes are also comparable to those of coordination compounds of 3d transition metals having similar structures. The decomposition and kinetic data are given in the Tables 11.2.5 and II.2..6. The initial decomposition and inflation temperature and fiee energy of activation have been used to determine the thermal stability of the metal chelates. Here in the present investigation based on the observation made by the other studies the relative thermal stabilities of the metal chelates of the dirnedone bis semicarbazone can be given as ZnL > NiL (H20)2 > CuL (H20) 2 Name of the Initial Inflation Free energy of complexes decomposition temperature activation (AG~), temperature 'C OC Wmole ZnL 160 250 150.12 Cu L(H20) 80 150 11 8.9 Ni L(H20) 80 120 11 0.22 Chapter 3 THERMAL DECOMPOSITION KINETICS OF Ni (11), Cu (11) and Zn (11) COMPLEXES OF DIMEDONE BIS -2-AMINOTHIOPHENOL In this chapter we focus on the study of the thermal activities of the complexes of the ligand, dimedone bis aminothiophenol. In this case TGIDTG were recorded in the static air condition with heating rate of 1 0 ' ~/m in. Coats Redfern equation is used to calculate the kinetic and thermodynamic parameters like frequency factor (A), order of the reaction (n), activation energy E, enthalpy of activation ( A H ~ , fiee energy of activation and entropy of activation (AS 3.T hermo gravirnetric analysis is further used for the structural perspective of the above said compounds. Here studies of the thermal decomposition of three representative complexes of dimedone bis aminothiophenol (H2DATP) of Cu (11) Ni (11) and Zn (11) are described. Experimental Preparation and structural analysis of the complexes were described in part 1. TG curves are presented in Fig 11.3.1-3.3 Kinetic and thermo dynamical parameters are calculated by using Coats Redfern equation with a personal system using a Microsoft Excel work sheet. Results and discussion In the case of copper complex, thermal decomposition curve consists of three stages, which is supported by the DTG data. First stage is due to the loss of 2H20 molecules. These two water molecules can be considered as the coordinated water molecule .The second stage represents the loss of dimedone part. In the third stage two molecules of aminothiophenol moiety are disappearing. The over all stepwise reaction can be represented 90-160°C CuL (H20) 2 dehydration + CuL CuL 160-28OoC partial decomposition -j intermediates Intermediates 340440oC fiml decomposition -) metal oxides DTG curve gives well-defined peak in the appropriate region. The over all loss of mass from the curve is 83.6% while the theoretical loss in mass during the decomposition of the complex is 81.5. Thermal decomposition data are given in the Table 11.3.1 .The data obtained by using Coats Redfern equation are given in the Table 11.3.2 In the case of Ni (11) chelate a three-stage decomposition pattern is observed First decomposition stage in this case is about 8. 5 %. The theoretical mass loss percentage for the two water molecule is 8.05 % .The peak temperature is about 100 'C. In this stage peak temperature, free energy of activation (AG~)a nd initial decomposition temperatures are very low which indicate lesser stability of the molecule. The second stage is a partial decomposition due to the loss of one dirnedone part and one ATP moiety. Third stage is the final decomposition which is due to the loss of arninothiophenol moiety and subsequent formation of corresponding oxide NiL (H20) + 80-160°C N ~ L 2 dehydration NiL 160-230°C partial decomposition + intermediates Intermediates 230-300°C final decomposition -) metal oxides The total mass loss is the 83.6 % is obtained for this step. This value is in accordance with theoretical loss percentage and pyrolysis data. The various data obtained during the thermal decomposition are given in the Tables. 11.3.3 and 11.3.4. Zn(I1) complex of H2DATP showed a two-stage decomposition curve. The first stage is loss of dimedone part and I molecule of the aminothiophenol part. Second stage decomposition is due to the loss of aminothiophenol moiety. At the end of the stage total mass is found to be 80%, where the theoretical percentage is 80.97 as given in the Table 11.3.5. ZnL partial decomposition -) '60-3700C intermediates Intermediates fiml decomposition + 370-5300C metal oxides The obtained values of various kinetic and thermodynamic parameters are given in the Table 11.3.6 . The initial decomposition temperature and inflation temperature and free energy of activation (AG~)h ave been used to determine the thermal stability of the metal chelates. By considering these factors the stability can be predicted as given ZnL > CUL (H20)2 > NiL (H2O) 2 Free energy of Name of the Initial Inflation activation (AG~), complexes decomposition temperature (first stage) temperature 'C OC Wmole Zn L 160 230 146.76 CuL(H20)2 90 120 11 6.47 NiL(H20)2 80 100 107.47 Chapter 4 THERMAL DECOMPOSITION KINETICS OF Ni (11), Cu (11), and Zn (11) COMPLEXES OF DIMEDONE BIS ZAMINOPHENOL In this chapter study of the thermal activities of the complexes of ligand, dirnedone bis aminophenol were conducted. Here also TG/DTG were recorded in the static air condition with heating rate of 1 0 ' ~/m in. Coats Redfem equation is used to calculate the kinetic and thermodynamic parameters like frequency factor (A), order of the reaction (n), activation energy E, enthalpy of activation (AH:), (AG:), (AS 3. Thermo gravimetric analysis is further used for the structural perspective of the above said compounds. Here Studies of the thermal decomposition of three representative complexes of dirnedone bis aminothiophenol (H2DAP) of Cu (11) Ni (II),and Zn (11) are described . Experimental Preparation and structural analysis of the complexes were described in part 1. Kinetic and thermo dynamical parameters were calculated by using Coats Redfern equation with a personal system using a Microsoft excel work sheet . Results and discussion Thermal decomposition curve of Cu (11) complex consists of three stages which is supported by the DTG data. First stage is due to the loss of two H20 molecules. These two water molecules can be considered as the coordinate water molecule .The second stage is a sharp fall due to the loss of 1 dimedone molecule. This stage is highly favored by entropy of activation. Due to the very fast reaction the percentage of mass fall was very rapid with maximum rate of reaction . In the third stage 2 aminophenol moieties are disappearing. The over all stepwise reaction can be represented 115-215°C CuL (H20) 2 dehydration CuL CuL partial decomposition -) 215-2450C intermediates Intermediates final decomposition -) 245"450C metal oxides DTG curve gives well-defined peak in the appropriate region. The over all loss of mass fiom the curve is 82.92%while the theoretical loss in mass during the decomposition of the complex is 81.04. The data obtained are given in the Tables. 11.4. land 11.4.2. In the case of Ni (11) chelates a three-stage decomposition pattern is observed. Mass loss in first decomposition stage in this case is about 10 %. The theoretical mass loss percentage for the two water molecule is 8.6 % The peak temperature is about 105 'C. In this stage peak temperature, fiee energy of activation (AG~)a nd initial decomposition temperatures are very low, which indicate that the lesser stability of the molecule. The second stage is a partial decomposition due to the loss of one dimedone and one aminophenol part. Third stage is the final decomposition which is due to the loss of aminophenol moiety and subsequent formation of corresponding oxide 65-125OC NiL (H20) 2 dehydration -) NiL NiL partial decomposition '25-2550C intermediates Intermediates final decomposition -) 255-5450C metal oxides The total mass loss is the 81.7% and this value is in accordance with theoretical loss percentage and pyrolysis data. The kinetic and thermodynamic parameters calculated. The data during the decomposition, various known thermodynamic and kinetic parameters are given in the Tables 11.4.3 and 11.4.4. Zn (11) complexes of H 2 D A P showed a two-stage decomposition curve. The first stage is loss of dimedone part and one arninophenol part. Second stage decomposition is due to the loss of aminophenol moiety. At the end of the stage total mass is found to be 78.0%, where the theoretical percentage is 78.9. ZnL 165-295oC partial decomposition -) intermediates Intermediates + 295-395oC final decomposition metal oxides The thermodynamic and kinetic parameters during this decomposition are given in the Table 11.4.5 and II.4.6.The activation energies obtained for the main decomposition stage of these three complexes are also comparable to those of coordination compounds of 3d transition metals having similar s t ruc t~ re s .~~ By considering the initial decomposition temperature and inflation temperature and f e e energy of activation (AG~)t,h e thermal stability of the metal chelates is as given below ZnL > CuL ( H 2 0 ) 2 > NiL ( H 2 0 ) 2 Decomposition pattern Name of the Initial decomposition Inflation Free energy of complexes temperature 'C temperature activation (AG~) , OC kJ/mole Zn L 165 215 145.98 Cu L( H 2 0 ) 2 115 155 123.54 Ni L( H20)2 65 105 105.37 Table 11.2.1 Temp Complex range Peak Stage in temp Loss of mass % Assignments TG 'C 'C FTro tTh eoretical I 80-180 150 9.9 10.2 ------- Loss of 2 H20 I1 180-380 360 52.1 51.4 - -- Loss of Dimedone+ ---p Semicarbazone part [CuL(H20)21 Loss of Sernicarbazone 111 380-560 400 15.5 16-21 ==-== part and subsequent formation of oxide 77.5 77.81 77.4 [CuL(H20)2]+CuO STAGE E 1"( A sec -1 A H ~ ( ~ J >A AS~(JK) G ~ ( ~ J ) Y n I 47.522 4.9* 1 o3 - 177.07 44.00 118.90 -0.9748 0.74 I1 70.671 6.21*103 -1 78.47 65.40 178.38 -0.9753 0.82 I11 62.27 6.04*1 0' -2 17.57 56.68 203.1 1 -0.9824 0.63 Figure 11.2.1 TG trace Cu DSC(H20)2 Temp Complex Stage range Peak in temp Loss of mass % Assignments TG 'C 'C Fro T$ Theoretical Pyrolysis I 80-160 120 09.40 10.38 LOSSo f 2 H20 Loss of 2 I1 160-340 280 40.60 42.1 1 Semicarbazone part [NiL(H20)2] Loss of ldirnedone I11 340-440 380 28.00 26.53 part and addition due to oxide formation 78.00 79.03 78.90 FiL(H20)2]-+NiO STAGE E (m) A sec -1 AHS(~J) A G(~k ~ ) AS:(JK) Y n I 47.58 1.43+E4 - 168.29 44.32 110.22 -0.9721 1 I1 74.27 4.72+E4 -160.56 69.67 158.46 -0.9684 0.87 I11 307.200. 2.62E+22 177.75 301.77 185.69 -0.9536 0.99 Figure 11.2.2 TG trace of Ni DSC(H20)2 Thermal decomposition data of Zn(I1) complex of dimedone bis semicarbazone- [ZnL 1 Temp Complex range Peak Stage in temp Loss of mass % Assignments TG From OC Oc TG Theoretical Loss of dimedone I 160-300 250 55.9 57 part+ one semicarbazone part Loss of second I1 425 19 18 semicarbazone part 300-450 and addition due to oxide formation 74.90 74.99 74.96 [ZnL] + ZnO Tihle: Itlab Kin,ndk pmarneters n lt he 4eeampositSos of eompta o f dimedane bis semtarhrrzoae-[ZnC1 STAGE E (kJK) A sec -1 AHY~J) AG$(~J) AS$(J~<) n I 46.81 1.92+E2 -205.84 42.47 150.12 -0.9687 0.47 I1 148.258 8.21+E8 -8 1.32 142.45 199.22 -0.9758 0.33 Figure 11.2.3 TG trace of ZnDSC Takle PPd.1 Themalt deeompodtlon data ofCu(1I) eomplm of dlmedone bis -2- a m h t h i a p h a n o ~ ( C ~ t L ~ H ~ Q ~ Temp Complex range Peak Stage in temp Loss of mass % Assignments TG OC OC TG Theoretical I 90-160 120 7.7 7.97 Loss of 2 molecules of water I1 160-280 240 23.1 23.9 Loss of 1 molecules of dimedone [CuL(H20)2] Loss of 2 molecules I11 340-440 400 52.8 50.49 of aminothiophenol + and addition due to oxide formation 83.6 8 1.49 83.22 [CUL(H~O)~]+CUO T a b 1 132 Khetle pammetars of the decompos2tlan otCu(P1) complex of dimedone bls, -2- arninathlophm&[CuL,(W~Q~ STAGE E (kJ/K) A sec - 1 AH$(~T) AS~(J/K) AG$(~J) Y n I 14.48 8.3E-2 -267.82 11.22. 116.47 -0.9806 0 I1 106.45 7.2E+08 -79.81 102.19 143.13 -0.9648 1 I11 32 1.43 3.9E+26 257.41 315.84 142.60 -0.9955 0.9 Figure 11.3.2 TG trace of [CUDATP(H~O)~] Temp Complex range Peak Stage Loss of mass % Assignments in temp O c From OC TG Theoretical Loss I I I 180-1601 100 1 8.5 1 8.05 1 I of 2 molecules of ( water Loss of 1 molecule of dimedone and 1 ATP part Loss of 1 ATP and formation of oxide TahIe BB3.4 Klnetile parsametera QF the deeampwdtim QFNlflQe camplex ~f dimedone MS- 2- lamintafhkphan&[NE&Hp8Bl A H ~ ( ~ J )A G ~ ( ~ J ) STAGE E (kJ/K) A sec -1 AS~(J/K) Y n I 40.1 1 1.052*E3 -1 88.91 37.01 107.47 -0.9882 0.76 I1 209.3 18 5E+20 146.58 205.30 134.50 -0.9806 0.82 I11 258.69 1E +23 193.57 254.68 161.18 -0.9633 0.97 - Figure 11.3.2 TG trace of [ NiDATP(H20)2] Tem Stage rang: Peak temp Loss of mass % Assignments in TG O c O c From TG Theoretical Loss of 1 molecule of I 160-370 230 56.20 55.10 dimedone And [ZA] 1 molecule ATP molecules Loss of 1 molecule I1 370-530 490 23.80 25.87 of ATP and formation of oxide 80.00 80.97 8 1.27 [ZnL] -+ ZnO L TaMe Ilt23b Kinetie pantmetcm sf the deccamposlt-ian of ZnQI1) eompJexm ofd imdone bl% -2- aminaXh%~phe~slc.[Znt,~ E STAGE A sec - 1 AS~(J/K) ~ ~ ' ( k l )A G'(~J) n I 45.71 4.4+E1 -2 17.42 41.74 146.76 -0.9812 0.8 I1 178.41 2E+10 -53.86 172.06 213.16 -0.9786 0.93 T~btXeE .4.1 Thermal deeompwiti~nd ata taPCu(XQ complex of dime4aae bis-2- amlnapheno l - f~~fEE~6~ Complex Stage Temp range in TG Peak temp Loss of mass % Assignments O c O c From TG Theoretical Loss of I 115-215 155 9.4 8.58 2 molecules of water Loss of I1 2 15-245 23 5 24.3 25.74 1 molecules of [CUL(H~O)Z] dimedone Loss of I11 2 molecules of 245-345 295 49.22 46.71 arninophenol and oxide formation 82.92 81.04 79.99[CuL(H20)2]-+CuO STAGE E A sec -1 AH$(~J) A G ~ AS$(JK) Y n I 61.123 7.9+E4 -154.15 57.56 123.54 -0.9798 0.82 I1 490.43 4.78E+48 682.56 486.21 139.47 -0.9839 0.98 111 114.06 16+E8 -93.00. 109.34 162.16 -0.9862 1 Figure 11.4.1 TG trace of [CUDAP(H~O)~] Tabte 11-43 Tbeinnal deeaapoAtion data of Ni(m emplex af dlmedone h&-2- a m i n 0 p t a e a o ~ f N U c ~ ~ 6 ~ Complex Temp Stage range Peak temp Loss of mass % Assignments in TG O c O c From TG Theoretical Loss of I 65-125 105 10 8.68 2 molecules of water Loss of 1 molecules of I1 125-255 205 49.4 51.60 dimedone [NiL(H20)21 part+ l molecule Aminophenol part 1 molecules of I11 255-545 263 20.6 21.70 aminophenol and oxide formation 8 1.7 8 1.98 8 1.64 [NiL(H20)2]+Ni0 STAGE E sec -1 AH$(~J) AG$(~J) A AS$(JK) Y n I 56.73 5.6+E5 -136.78 53.59 105.30 -0.9955 0.65 I1 601.62 3.99E+60 910.78 597.39 134.71 -0.9882 0.95 I11 394.83 5.83E+35 434.89 390.38 157.27 -0.9284 0.99 Tabk X1,4,% Thermal deeamposition data of&(lI) eomplex of dimedone bk-2-antinophenol IBLl Complex Temp range Stage in^^ Peak temp Loss of mass % Assignments O c O c From TG Theoretical Loss of 1 dimedone part I 165-295 215 55.7 55.52 and 1 aminop heno l [ZnLl part 1 arninophenol part and I1 295-395 355 22.3 23.4 formation of oxide 78.0 78.9 79.86 [ZnL] + ZnO AH$(~J) STAGE E (kJK) A sec -1 AS$(JK) AG$(@ Y n I I 124.32 1.80E+10 -52.70 120.26 145.98 -0.9848 0.91 11 210.08 1.37E+16 57.82 205.65 169.33 -0.8775 0.99 Figure 11.4.3. TG trace of [ZnDAP] References 1) Christian,S.Soil Sci. Soc. Am. J. 2004,68,16561661. 2) Vadim, M.; Serge, B.; Michel, L. B.; Sophie, D.; Jaroslav, S. Phys. Chem. Chem. Phys. 2000,2,4708-47 16. 3) Yilmaz.1.; Cukurovali, A. Polish J. Chem. 2004,78,663-672. 4) Marisa ,S. C.; Clovis A. R.; Valentina, C. M. G.; Henrique, E. Z. Quimica Nova. 1999, 22. 5) Osman ,A.H.; Aly, A. A.M. ; El-Mottaleb,M.A. ; Gouda G. A. H., Bull. Korean Chem. Soc. 2004,25, 1. 6) lffet Sakyan.; Gunduz,N.; Gunduz,T. Ankara University, Science Faculty, Department of Chemistry, Ankara, Turkey . www.ankara.edu.tr .2004. 7) Brown, M.E. Introduction to Thermal Analysis Techniques and Applications Series; Hot Topics in Thermal Analysis and Calorimetry, 2002 , 1 , 280 pp. 8) Duval , C. Inorganic Thermogravimtric Analysis ;New york. Elsevier,l963. 9) Smoothers, W.J.; Yaochiang, M.S. Hand book of differential thermal analysis : Newyork, chemical publishing CO, 1966. 10) Garn,P.D. Thermo analytical methods of analysis ;N ew York: Interscience, 1964. l 1) Schulze, D. Differential thermal analyzer, Berlin, 1969. 12) Wendlandt, W. W. Inorg.N ucl. chem. 1963,25,545. 13) Horowitz, H . H.; Metzger, G. J Anal. Chem. 1963,35, 1464. 14) Coats, A.W.; Redfern, J.P. Nature. 1964. 201,68. 15) Maccallum, J.R .; Tanner, J. Europian.po1ym.j. 1970,61,1033. 16) Soliman, A.A.; Linert,W. Thermochimica Acta. 1999,338,67,75. 17) Atkins .P.W . Physical chemistry ;Oxford university press, 1075 pp . 18) Sadeek ,S.A.; Refat, M.S.; Teleb, S.M. Bulletin of the Chemical Society of Ethiopia. 2004, 18,2, 149-156. 19) Jeong,B.G etal. Bull. Korean. Chem. Soc. 1996 ,l 7, 173 - 179 . 20) Parra, M.eta1. j. Chil. Chem. Soc. 2003,48 , l . 21) Rao,N.S.;Reddy ,M.G. Biol Met. 1990,3,1,19-23. 22) Friscic, T.; Lough, A. J. ; Ferguson, G.; Kaitner, B. Acta Cryst. 2002, C58, 313-315. 23) Al-Shihri,A. S. M.; Abdel-Fattah, H. M. Journal of Thermal Analysis and Calorimetry. 2003,7 1 ,2 ,643 - 649 . 24) Ascenzo ,G.D.; Wendlandt,W.W . Anal. Chem.Acta. 1970,50,75. 25) Chang,F.C.;Wendlandt, W.W. Thermochim.A cta. 1971,293. 26) Perry. D.L.; Vaz ,W. C.; Wendlandt, W .W. Thermochim.acta. 1974,9,76. 27) Nikolaev, A.V. ; logvinenko V. A.; Myachina, L.I. Thermal analysis ;N ew York: Academic Press, 1969,779. 28) Vatsala, S.; Pararneswaran, G. .IT hem. Anal. 1986,31 ,883. 29) Sheshadri Naidu, R .; Ragavanaidu.R. Indian J. Chem. 1967, 15 A ,65. PART III ANTIFUNGAL ACTIVITIES OF SCHIFF BASE COMPLEXES Abdul Jaleel.U.C “Synthesis, thermal and spectral studies of some transition metal complexes of schiff bases” Thesis. Department of Chemistry , University of Calicut, 2005 " f - PART I11 Antifungal activities of Schiff base complexes Chapter. 1 INTRODUCTION Damages due to diseases play a major role in limiting black pepper (Piper nigrum L.) production in India. Several diseases caused by fungi, virus and mycoplasma affect black pepper, besides nutritional disorders. Foot rot is the major disease of black pepper in India. It is popularly known as quick wilt and is caused by he fungus Phytophthora capsici. This disease is prevalent during southwest monsoon in all black pepper growing tracts of south India and is characterized by leaf infection with characteristic fimbriate margin and foot rot1-'. Crop losses due to foot rot disease in Kerala is estimated to be 10% of the total production 6 . Phytophthora as plant pathogen Fungi are a group of spore bearing organisms lacking chlorophyll. They are heterotrophic in their nutrition. They either infect living organisms as parasite or utilize dead organic matter as saprophytes to obtain their food. The thallus or body of the fungus is called as mycelium that consists of a large number of branched tubular, hyaline structures each of which is individually called as hypha. Many fungi are parasitic on plants causing severe diseases and crop loss *' ' . Phytophthora is a oomycetous hngus which cause severe diseases in many horticultural crops worldwide 9. Phytophthora species cause severe diseases on various crops2.~anyo f the plantation and spices crops in India are affected by Phytophthora and resulting in economic crop loss. They affect rubber, coconut, arecanut, black pepper, cardamom, vanilla etc. Therefore the study of their biology and control is highly significant. Ribeiro described various procedures for the study of Phytophthora l'. Biology of Phytophthora Phytophthora is oomycetous fungus, which is a group of mycelial organisms and represents a unique evolutionary line. In addition to being dispersed via zoospores and generating thick walled sexual oospore, they posses features such as cellulose (P -, 1,4 glucans) in their cell wall, vegetative diploidy, heterokont flagella l '-l4 ,t ubular mitochondrial cristae". Phytophthora species do not synthesise sterols but require an exogenous source of p hydroxy sterols 16. Phytophthora reproduce by vegetative, asexual and sexual methods. Vegetative growth of Phytophthora depends upon the nutrient status. The asexual method of reproduction is by sporangium or more specifically a zoosporangium, which means a vessel containing zoospore. Sporangia are born on long stalks called sporangiophores. In some species new sporangiophores emerge through the base of the old sporangium fkom which uninucleate zoospores have been released. In other species new sporangiophores arise just beneath the base of the old sporangium, i.e. they are sympodial and produce more sporangia successively. It varies in size and shape 9,'0. Sporangium germinates in aqueous solutions or in agar media by the production of germ tube that usually emerges fkom the tip of the sporangium (direct germination). In aqueous medium sporangium produces uninucleate biflagellate zoospores that are released into the water (indirect germination). The zoospores are renyform in shape with two heterocont flagella emerging fiom the concave side. In Phytophthora a long whiplash characterize one of the flagella and shorter tinsel the other 9*' '. Zoospores swim for hours and eventually cease to swim, round up and within minutes develop a cell wall. At this stage the spore is called a cyst. Encystment can be induced by agitation either produced artificially by shaking zoospore in a flask or naturally by their bumbing against solid surface. Eventually their flagella are shed and cysts germinate by producing germ tubes. Occasionally another zoospore may form within the cyst and be released. Zoospores are considered to be the major infectious propagules 9210. The chlamydospores are spherical to oval. It is hyaline or brown and has either thin or thick wall. Chlamydospores may form terminally at the tips of hyphae or may be intercalary (between the tip and base of hyphae) 93'0. Phytophthora reproduce by sexual spores under suitable environmental conditions. The sexual structure of Phytophthora is composed of an antheridium (male component) and an oogonium (female component). The oogonia are usually globose or subglobose but are occasionally pyriform. The oogonium is delimited from the hyphae by septum; the antheridium is delimited by a septum that attaches to the oogonial incept. Oogonial incept grows through the antheridial incept. This type of antheridium is classified as amphigynous (surrounding the female). In some species antheridium attaches to the oogonium by contact to the lower hemisphere side of the oogonium and is called paragynous (beside the female). Reduction division or meiosis of the nucleus occurs in the coenocytic antheridia and oogonia. A fertilization tube fiom the antheridium ruptures the oogonial wall and deposits the antheridial nucleus. The haploid nuclei fiom the antheridium and the oogonium are fused to form the diploid nucleus. A nucleus presumed to be the fusion nucleus remains along oogonial cytoplasm. The single egg that forms within the oogonium is globose and characteristically develops a thick inner wall composed largely of P +l-3 glucans. The diploid oospore germinates under suitable conditions by the production of single or multiple germ tubes at the tips. Some species of Phytophthora are homothallic where as others are heterothallic. P. Capsici is heterothallic ,however only one mating types is present in India and therefore sexual reproduction is not reported 9. Foot rot of black pepper caused by Phytophthora capsici Phytophthora capsici is a devastating soil born pathogen that affects all parts of the black pepper plant. Infection of the under ground portion remain undetected until symptoms appear on the aerial portion. This renders the control measures taken after noticing the symptoms ineffective. Its infection on under ground parts like roots and collar (foot) result in the root rot and foot rot respectively. Aerial infections on leaves, spikes and stems also occur and spread rapidly under favourable conditions causing yellowing and wilting of leaves followed by def01iation.l'~ Phytophthora capsici occur both in the nursery as well as in the main field. The fbngus survives in the infected plants and soil for a period of more than a year. The pathogen spreads mainly through rain and water splashes. High rainfall, high relative humidity, low temperature and shorter duration of sunshine are the factors that favour the spread of the disease in black pepper plantation. Climatic conditions influence the life cycle of Phytophthora, its pathogenicity and the epidemic it causes. Fungus remains dormant in the form of resting spores during unfavorable seasonsSl8. Sporangia are predominantly tapered at the base and are caducous with long pedicels varying in length. Sporangia are extremely variable in shape and dimension. Black pepper isolates of Phytophthora produce sporangia on sporangiophores that are characteristically umbellate. Phytophthora capsici is predominantly heterothallic and antheridia are amphigynous. Oogonia are spherical or sub spherical and hyaline to brown in colour. Dimension of oogonia fiom different host vary fiom 23-50 pm9310P. hytophthora capsici has four different phases of growth, which are mycelial growth, sporangial formation, zoospore liberation and zoospore germination. A compound inhibiting one of these phases could be useful as an antifungal agent l9 . Biological control Although chemical control is feasible against Phytophthora, owing to the health hazardous nature of chemical fungicides, biological control has emerged as an alternative to chemical control 20. Gliocladium virens, Trichoderma spp, vesicular arbuscular mycorrhizae and Pseudomonas fluorescens etc are used against Phytophthora capsici. Trichoderma spp inhibited mycelial growth and production of sporangial production in P. capsici 21. Biocontrol agents produce enzymes and secondary metabolites, which inhibit plant pathogens. It has been reported that application of nitrogenous organic substance suppresses Phytophthora population in the soil 21. Extract of garlic has been reported to be effective against Phytophthora sp 22 . Chemical control During the past two decades many chemicals having selective toxicity to fungi were developed and some of them are used as fungicide in commercial scale. Fungicides are compounds that destroy a fungus or inhibit, suppress its growth. For control of Phytophthora infections, a number of fungicides are being used. They are often classified as contact and systemic fungicides 9. The contact hngicides used are copper compounds especially Bordeaux mixture, Copper oxychloride and Cuprous oxide 23, Organotin compounds, Dithiocarbamates (Zineb, Maneb, Mancozeb), Chlorothalonil and p hthalimideS (captan, captofol and f 0 1 ~ e t ) ~ ~O.r ganotin compounds are particularly effective antisporulant fungicides 25. Ziram and Ferbam are dialkyldithiocarbamates while Nabam, Zineb and Maneb are dialkyl bis dithiocarbamates. The dithiocarbamates are ideal to copper hngicides because they are much less phytotoxic. Chlorothalonil has greater persistence in rainy weather than other contact fungicides 26. Another class of fungicide is systemic fungicides. These are the compounds, which can be taken up through roots, stems and leaves. Comparing with protective fungicides, systemic hngicides are less subject to loss by rainfall and can suppress the pathogen even after the infection. The systemic fungicides effective against Phytophthora are classified into several groups. These include the carbamates (Prothicarb and Propamocarb) 27>28 isoxazoles (Hymexazol), cyanoacetamide oximes (Cymoxanil), ethyl phosphonates (Fosetyl Al) and phenyl amides (Metalaxyl and several related compounds) 26 ,29 Metalaxyl (DL-methyl - N- (2,dimethyl - phenyl)- N (2- methoxyacetyl) a1aninate)-a phenyl amide- was the most effective hngicide on mycelial growth of Phytophthora capsici. Metalaxyl was also found to be compatible with Furadan and Phorate. Among the fungicides Metalaxyl-Ziram or a similar combination has been proposed as a major component in the integrated management of Phytophthora infections in black pepper 'O. Even thorough several chemical controls are available in commercial scale, scientists and farmers are facing major hindrances like phytotoxicity, environmental pollutions due to this compounds. The possible means for the solving this intricacy is the improvement of biological control or development of chemical control with lesser hazardness. On this context search for a new chemical control will be highly justifiable. Such a development will be an added advantage in the drug research against the oomycete pathogen like Phytophthora capsici. Coordination compounds Coordination compounds in general and derived Erom Schiff base in particular has played an important role in the development of anti fungal agents. The biological activities of some transition metal complexes with Schiff bases have been reported. Schiff base complexes of Copper (11), Nickel (11), Vanadium (IV) and Uranium (VI) derived Erom phenyl butazone and 2-amino phenol shows antibacterial activity against E. coli3'. Among the Schiff base complexes of first transition series Nickel complex of N-benzoyl - N' - (2 - aminophenyl) thiocarbamide has been shown to exhibit antifungal activity. The organism, Pyricularia oryzae which cause rice blast and Helminthosporium oryza which cause brown leaf spot can be controlled with Ni (11) complexes of 1- phenyl-3-methyl4nitroso-2-pyrazolin-5-one and 3-methyl- 4-nitroso-2- pyrozolin-5-one 32. Copper complexes of the ligands N-benzoyl-N'- (2-aminophenyl) thiocarbamide is found to be effective compounds for Aspergillus niger, Fusarium oxysporum and Helminthosporium oryzae 32. Copper complexes are reported to be more active fungicides than similar Iron, Cobalt and Nickel complexes. The complexes were found to be more effective than the free ligands3).T his findings turn out to be another hope in the tackling of plant and animal diseases. So coordination compound have a wide possibility in the exploration of new antifungal, antibacterial, antiviral agents. Mechanism of antifungal activity The study of the fungicide is now bound for the development of mode of action of drugs in a more precise way. This can be achieved by studying the percentage of inhibition by different compounds on a trial and error method., and subsequent determination of mode of action by choosing the most effective drug34. Specific determination of the mechanism of antifungal activity may lead to the better development of extra apposite antifungal agents. Coyle Barry et al., studied the mode of antifungal activity of 1,10 phenanthroline and its Cu (11), Mn (11) and Ag (I) complexes against the pathogenic yeast Candida albicans and showed that all the complexes promote reduction in the levels of cytochromes b and c in the cells, while the Ag (1) complex lowers the amount of cytochromes aa3. They damage mitochondria function and uncouple respiration 34. Similar studies in Phytophthora capsici will create way for the development of antifbngal agents. Scope of present investigation In spite of the popular trend for completely organic and pesticide fiee farming, the diseases like foot rot of black pepper will probably never be completely controlled without fbngicides since the pathogen spreads rapidly under favorable conditions. But the hazardness of the presently using fungicides /pesticides creates much anxiety among the public. So the pursue for a hazardous fiee chemical control is the next pragmatic way out in the warfare against fungi. The developments of antifungal agents look for a special attention in molecular and genetical level also. So the studying and revealing the exact mode of the anti fungal activity of different compounds will further help the above said search in the new direction In view of this, a group of ligands and their metal complexes were tested against the mycelial growth of Phytophthora capsici. Based on the lead fiom the preliminary study a detailed study was under taken to frnd out the inhibitory effect of these ligands and metal complexes of Copper, Cobalt, Nickel on the various stages of the growth of Phytophthora capsici viz. mycelial growth sporangial production, zoospore liberation and zoospore germination. CHAPTER. 2 MATERIALS AND METHODS In this chapter anti fungal activity of transition metal complexes of dimedone - bis -2-aminophenol (HzDAP), Cyclohexanone -2-aminophenol (HCAP), pyrolidone -2-aminophenol (HP AP), dimedone bis -2-aminothiophenol (H2DATP) are described. The details of preparation and characterization of the above-mentioned complexes are presented in Part I. It was found that all complexes were soluble in DMSO. Standard solutions of complexes were prepared in DMSO and diluted to the required concentration using sterile distilled water. The complexes in required quantity were incorporated with carrot agar medium to study its effect on various growth stages of Phytophthora capsici infecting black pepper. CULTURE MEDIA Carrot agar was used as the culture media to grow P. capsici. The materials required for the preparation of 1 liter of carrot agar are, Carrot - 200g Agar -20 g Distilled water - 1 liter The 200 g of carrot was pealed and cut into small pieces. The carrot was I ~ grinded and about one liter of juice was obtained. The carrot juice was then boiled , l and 20g of agar was added while stirring. This was distributed in to conical flasks and sterilized by autoclaving at 12 1'C (1 51b) for 15 minutes. ISOLATION OF Phytophthora capsici Infected roots of diseased plants were collected and brought to the laboratory. It was washed several times with sterilized water and small pieces were cut fiom - advancing margins of lesions. It was then sterilized in 0.1% HgCI2 for 30 seconds and washed with three charges of sterile distilled water and blot dried. These bits were placed on Carrot Agar media containing PVPH and incubated at 2 4 ' ~f or 48- 72 hours. The Phytophthora was sub cultured into carrot agar slants for fhrther studies. BIOASSAY The thermo labile nature of the complexes was noted and it was found that except CO (11) all other complexes were thermo stable. Ligand was found to be thermo labile. Hence, all fhther studies were conducted by adding the solutions of these complexes to carrot agar media before sterilization for thermo stable complexes. For thermo labile complexes, it was added just before pouring the media into plates. The effect of these complexes on mycelial growth, sporulation (sporangial production), zoospore release and zoospore germination of Phytophthora capsici was studied by incorporating the complexes into Carrot Agar media as specified. The complexes and ligands were dissolved in DMSO-water mixture (1:40 ratio) to form a stock solution of 2000ppm. From the stock solution, different dilutions were made. IN-VITRO EFFECT OF COMPLEXES ON VARIOUS STAGES OF PHYTOPHTHORA CAPSICI Mycelial growth Poisoned food technique was used for the mycelial growth study 19. The test solutions were mixed with carrot agar to obtain concentrations ranging from 250 to 1000 ppm so as to form a final volume of 50ml medium. The amended medium was poured into petriplates (90mm) @20ml per plate. Inoculum plug of Phytophthora capsici, 5mm in diameter, were taken from the periphery of 48-hour-old culture and placed in the centre of the petriplates. Three replications were maintained. Carrot Agar plates without test solutions and inoculated with culture disc were used as the control. The plates were incubated at 2521 '~i n dark and growth of the colony was measured after 72 hours of inoculation. The radial growth of colony was measured fiom three sides of the plate and the mean of these three readings were taken as the radius of the colony. The growth of the colony in the control sets were compared with that of various treatments and the percentage of inhibition was calculated using the formula, ((C-T) / C) X 100 Where 'C' is the radial growth in the control, 'T' is the radial growth in the complex solutions. Sporangial production For studying the effect of metal complexes on spomlation, the Phytophthora capsici was grown on carrot agar in dark for 48 hour at 2 5 ' ~ .F ew discs of 5mm size taken fiom the edge of 48hr old culture were placed in sterile petriplates containing l Oml test solutions of different concentrations and incubated under fluorescent light for 24 hour. In control, the discs were placed in 10ml of sterile distilled water. Number of sporangia produced per microscopic field (20 X) was counted and the average number of sporangia per field was calculated and compared with that of control 'O. The percentage inhibition over control was calculated using the formula ((C-T) / C) X 100 Where 'C' is the number of sporangia in the control, 'T' is the number of sporangia in the complex solutions. Zoospore Release1 Indirect Germination of Sporangia To study the effect of complexes on zoospore release (indirect germination of sporangia), 5mm discs cut fiom the periphery of 48hour old culture was allowed to sporulate as described above. Cold shock treatment was given by keeping the petriplates in the freezer at 4 ' ~fo r 10 minutes. These plates were then taken and incubated at laboratory temperature for 30 minutes before observation. Distilled water instead of test solution was used in control. Zoospores from sporangia were released after the cold shock. The number of sporangia released are counted per microscopic field. Also noted was the number of sporangia do not opened1'. Percentage inhibition of zoospore release was calculated by using the formula ((C-T) 1 C) X 100 Where 'C' is the number of sporangia opened in the control, 'T' is the number of sporangia opened in the complex solutions. Zoospore germination The effect of test solutions on germination of zoospores was studied. The zoospores were produced by following the above procedure and collected in vials. The zoospore settled at the bottom were collected and placed in clean cavity slides containing 50p1 of test solution. The zoospores were taken in cavity slides containing different concentration of test solution ranging from 250-1000ppm concentrations and incubated for 12 hours at 24 '~ . Replicates were also kept for all the concentrations. In each slide, 5 microscopic fields were observed for counting the number of zoospores germinated l'. Percentage inhibition of zoospore germination was calculated using the formula ((C-T) I C) X 100, where 'C' is the number of zoospores germinated in the control, 'T' is the number of zoospores germinated in the complex 1 solutions. In order to understand the level of difference in the percentage of inhibition of complexes and their corresponding metal salts, a detailed study about the extent of inhibition were conducted on Phytophthora capsici by using the corresponding metal acetates.