Synthesis, Spectral Characterization, Structural Studies and Biological Investigations of Transition Metal Complexes of Some Acid Hydrazones

This study concentrates the chemical properties of hydrazones due to its chelating capability and their pharmacological applications. Studies cover the preparation of different acid hydrazones and their structural studies and studies on their antimicrobial activity, synthesis and spectral characterization of different complexes of copper oxovanadium, manganese, nickel etc. Effect of incorporation of heterocyclic bases to the coordination sphere, change in the biological activity of acid hydrazones upon coordination, development of X-ray quality single crystals and its X-ray diffraction studies, studies on the redox behavior of the coordinated metal ions and correlation between the stereochemistry and biological activities.

Structural and Spectral Investigations of Transition Metal Complexes Of Di-2-Pyridyl Ketone N (4), N (4)-Disubstituted Thiosemicarbazones

The study deals with structural and spectral investigations of transition metal complexes of di-2-pyridyl ketone N(4),N(4)-disubstituted thiosemicarbazones. The main objective and scope of the work deals with di-2-pyridyl ketone N(4),N(4)-disubstituted thiosemicarbazones are quardridentate NNNS donor ligands. To chosen this ligand for study because, the ligands are prepared and characterized for the first time, since there are two pyridyl nitorgens, dimmers and polymers of complexes may result leading to interesting structural aspects. The work includes the preparation of the thiosemicarbzones and their structural and spectral studies, synthesis and spectral characterization of complexes of copper(II),,nickel(II),manganese(II), dioxovanadium(V),cobalt(III),zinc(II),cadmium(II) of the ligand HL, synthesis and spectral characterization of complexes of copper(II),manganese(II), of the ligand HL and the development of X-ray quality crystals and its X-ray diffraction studies. The structural characterization techniques are elemental analysis, conductivity measurements, magnetic measurements, electronic spectroscopy, H NMR spectroscopy, Infrared spectroscopy and X-ray crystallography.

Spectral studies and crystal structures of some transition metal complexes of N4-substituted semicarbazones

The present work is concentrated on the studies of two novel semicarbazones, di-2-pyridyl ketone-N4-phenyl-3-semicarbazone (HL1) and quinoline-2-carboxaldehyde-N4-phenyl-3-semicarbazone (HL2). The compositions of these semicarbazones were determined by the CHN analyses. For the characterization of these compounds we have used IR, UV and NMR spectral studies. The molecular structure of quinoline-2-carboxaldehyde-N4-phenyl-3- semicarbazone (HL2) was obtained by single crystal X-ray diffraction studies. Also, we have synthesized Zn(II), Cd(II), Cu(II), Ni(II), Co(II) and Mn(II) complexes of these semicarbazones, HL1 and HL2. These complexes were characterized by various spectroscopic techniques, magnetic and conductivity studies. We could isolate single crystals of some Zn(II) and Cd(II) compounds suitable for X-ray diffraction studies. For other complexes we could not isolate single crystals of good quality for single crystal X-ray diffraction studies.

Investigations on the Structural, Spectral and Magnetic Interactions of Transition Metal Complexes of Multidentate Ligands from Di-2-pyridyl ketone and N(4)-substituted Thiosemicarbazides

The present work deals with the investigations on sthe structural spectral and magnetic interactions of transition metal complexes of multidentate ligands from D1-2-pyridyl ketone and N(4)-Substituted thiosemicarbazides.Thiosemicarbazones are thiourea derivatives with the general formula R2N— C(S)—NH—N=CR2. In the solution state, the thiosemicarbazones exhibit the thionethiol tautomerism similar to the keto-enol tautomerism, and in solution state the thiol form predominates and a deprotonation at the thiolate group in alcoholic medium enhances the coordination abilities ofthe thiosemicarbazones.The magnetochemistry of metal complexes of di-2-pyridyl ketone is a current hot subject of research, which mainly owes to the excellent structural diversity of the complexes ranging from cubanes to clusters, with promising ferromagnetic outputs.Only few efforts were aimed at the magnetochemistry of metal complexes of thiosemicarbazones, and that too were concerned with the complexes of bisttltioscinicarbazones). However, as far as the monothiosemicarbazones are concerned, the magnetochemistry of transition metal complexes of di-2-pyridyl ketone thiosemicarbazones turned up quite unexplored. Consequently, an investigation into it appeared novel and promising to us and that prompted this study, which can be regarded as the initial step towards exploring the magnetochemistry of thiosemicarbazone complexes, especially of di-2-pyridyl ketone derivatives.We could successfully isolate single crystals suitable for X-ray diffraction for the first three ligands. To conclude, we have synthesized some new thiosemicarbazones and their transition metal complexes and studied their structural, spectral and magnetic attributes. Some ofthe complexes revealed interesting stereochemistries and possible bridging characteristics with spectroscopic evidences. Unfortunately, single crystal Xray diffraction studies could not be carried out for many of these interesting compounds due to the lack of availability of suitable quality single crystals. However, the magnetic studies provided support for the proposed stereochemistry giving evidences for their magnetically concentrated nature. The magnetic susceptibilities measured at six different temperatures in the 80-298 K range are fitted into different magnetic equations, which provided an idea about the magnetic behavior of the compounds under study. Some of the copper, oxovanadium, nickel and cobalt complexes are found to possess anomalous magnetic moments, i.e., they revealed no regular gradation with temperature. However, some other copper complexes are observed to be antiferromagnetic, due to super-exchange pathways. The manganese complexes and one of the cobalt complexes are also observed to be antiferromagnetic in nature. However, some nickel complexes have turned up to be ferromagnetic. Accordingly, the versatile stereoehemistry and magnetic behavior of the complexes studied, prompt us to conclude that the transition metal complexes of di-2-pyridyl ketone thiosemicarbazones are promising systems for potential magnetic applications.

Transition metal complexes of some N4-phenylsemicarbazones: crystal structures and spectral studies

The unusual coordination modes of semicarbazones when bound to metals, the wide applications and structural diversity of metal complexes of semicarbazones provoked us to synthesize and characterize the tridentate ONO and NNO-donor semicarbazones and their transition metal complexes. This work is focused on the studies on complexes of three N4-phenylsemicarbazones synthesized by changing the carbonyl compounds. This work is concerned with the studies of two new semicarbazones, 2- formylpyridine-N4-phenylsemicarbazone (HL1) and 3-ethoxysalicylaldehyde- N4-phenylsemicarbazone (H2L2) and a reported semicarbazone 2-benzoylpyridine-N4-phenylsemicarbazone (HL3) [29]. The compositions of these semicarbazones were determined by the CHN analyses and IR, UV and NMR spectral studies were used for the characterization of these compounds. The molecular structure of 3-ethoxysalicylaldehyde-N4-phenylsemicarbazone (H2L2) was obtained by single crystal X-ray diffraction studies. Also, we have synthesized Cu(II), Cd(II), Zn(II) and Ni(II) complexes of these three semicarbazones. The complexes were characterized by various spectroscopic techniques, magnetic and conductivity studies. We could isolate single crystals of some complexes of all metals suitable for X-ray diffraction studies. This thesis is divided into six chapters.

Growth and characterisation of tin dichalcogenide crystals

During the past few decades, a wide spread interest in the structural, optical, electrical and other physical properties of the transition metal dichalcogenide layer compounds has evolved. The members of this family of compounds can be regarded as strongly bonded two dimensional chalcogen-metal~chalcogen layers which are loosely coupled to one another by the weak ven der Waal's forces. Because of this type of bonding, the crystals are easily cleavable along the basal plane and show highly anisotropic properties. This thesis contains the growth and the study of the physical properties of certain tin dichalcogenide crystals (SnS2 and SnSe2). Tin disulphide and tin diselenide crystallize in the hexagonal CdI2 type crystal structure. This structure consists of layers of tin atoms sandwiched between two layers of chalcogen atoms. A tin atom is surrounded by six chalcogen atoms octahedrally.In the layers the atoms are held together by covalent bonding and in between the layers there is van der Waal's bonding.

Growth and characterisation of tin dichalcogenide crystals

During the past few decades, a wide spread interest in the structural, optical, electrical and other physical properties of the transition metal dichalcogenide layer compounds has evolved. The members of this family of compounds can be regarded as stronglybonded two dimensional chalcogen-metal-chalcogen layers which are loosely coupled to one another by the weak van der Waal's forces. Because of this type of bonding, the crystals are easily cleavable along the basal plane and show highly anisotropic properties. This thesis contains the growth and the study of the physical properties of certain tin dichalcogenide crystals (SnS2 and Snsea). Tin disulphide and tin diselenide crystallize in the hexagonal CdI2 type crystalstructure. This structure consists of layers of tin atoms sandwiched between two layers of chalcogen atoms. Aitin atom is surrounded by six chalcogen atoms octahedrally. In the layers the atoms are held together by covalent bonding and in between the layers there is van der Waal's bonding.

Structural, Spectral, Biological and Electrochemical Studies Of Some 3d Transition Metal Complexes of O-N-S and N-N-S Donor Ligands

The primary aim of these investigations was to probe the spectroscopic, electrochemical, biological and single crystal X-ray diffraction studies of some selected transition metal complexes of 4N-monosubstituted thiosemicarbazones. Transition metal complexes with thiosemicarbazones exhibit a wide range of stereochemistries and possess potential biological activity. Metal complexes of thiosemicarbazones are proved to have improved pharmacological and therapeutic effects. The studies are conducted to bring about a fair understanding of the structure activity relationship and to develop certain effective and economical metal-based antimicrobial agents. Study showed that the thiosemicarbazones have antibacterial, antiviral and antiproliferative properties and hence used against tuberculosis, leprosy, psoriasis, rheumatism, trypanosomiasis and coccidiosis. Certain thiosemicarbazones showed a selective inhibition of HSV and HIV infections. The insolubility of most thiosemicarbazones in water causes difficulty in the oral administration in clinical practice. Transition metal complexes are found to have more activity than uncombined thiosemicarbazones. They exhibit a variety of denticity and can be varied by proper substitution. The stereochemistry assumed by the thiosemicarbazones during the coordination with transition metal ions depends on the factors such as preparative conditions and availability of additional bonding site in the ligand moiety and charge of the ligand. The resulting complexes exhibited a wide range of stereochemistries and have biomimic activity and potential application as sensors.

Electro-Optical Properties of Metal Phthalocyanines and Naphthalocyanines

The thesis deals with the preparation of chemical, optical, thermal and electrical characterization of five compounds, namely metal free naphthalocyanine, vanadyl napthalocyanine, zinc naphlocyanine, europium dinaphthalocyanine, and europium diphthalocyanine in the pristine and iodine-doped forms. Two important technological properties of these compounds have been investigated. The electrical properties are important in applications sensors and semiconductor lasers. Opto-thermal properties assume significance for optical imaging and data recording. The electrical properties were investigated by dc and ac techniques. This work has revealed some novel information on the conduction mechanism in five macrocyclic compounds and their iodine-doped forms. Also useful data on the thermal diffusivity of the target compounds have been obtained by optical techniques.

Synthesis and Characterization Of Some Transition Metal Complexes Of Multidentate Ligands

Coordination chemistry of schiff bases is of considerable interest due to their various magnetic, catalytic and biological applications. Here it describes the spectral characterization of schiff bases and its Mn (II), Cu (II) and Ni (II) complexes. Then synthesis and spectral characterization of Zn (II), Cd (II) and Co (II) complexes of schiff base derived from 3-Formylsalicilic Acid and 1,3-diaminopropane. Then it discusses the synthesis and spectral studies of Copper (II) complexes of 2-Hydroxyacetophenone N-phenyl semicarbazone. Finally it discusses the synthesis and spectral characterization of Co (III) complexes of salicylaldehyde N-phenyl semicarbazone. The preparation and characterization of Cobalt (III) complexes of salicylaldehyde, N-phenylthiosemicarbazone containing hetrocyclic bases phenalthroline and bipyridine. Thiocyanate, azide and perchlorate ions act as coligands. Elemental analysis suggests +3 state for Cobalt. HNMR, IR and UV-visible spectra characterize the complexes.

Studies on Catalysis by Vanadia Supported On Metal Oxides

Catalysis is an essential technology in manufacturing industries. The investigation based on supported vanadia catalysts and it’s sulfated analogues. Vanadia is a transition metal oxide and is used in oxidation reactions in chemical industry. It is more active and selective catalysts on suitable supports. The work deals with preparation of vanadia incorporated tin oxide and zirconia systems by wet impregnation. Physico-chemical characterization using instrumental techniques like BET etc. The surface acidic properties were determined by the ammonia TPD studies, Perylene absorption studies and Cumene conversion reaction. The catalytic activities of the prepared systems are tested by Friedel-Crafts benzylation of arenes and Bechmann rearrangement of Cyclohexanol oxime. Here the rector reactions are relatively rare. So to test the application of the catalyst systems for the selective oxidation of cyclohexanol to cyclohexanone and finally evaluate the catalytic activity of the systems for the vapour phase oxidative dehydrogenation of Ethylbenzene, which leads to the formation of Industrially important compound ‘styrene’ is another objective of this work

Studies on Some New Metal-Hydrazone Complexes and Their Zeolite Encapsulated Analogues

The thesis deals with the synthesis, characterization and catalytic activity studies of some new Fe (III), Co (II), Ni (II) and Cu (II) complexes of hydrazones and their zeolite encapsulated analogues. Hydrazones have diverse applications in biological, non-biological and biochemical front. During the present study three hydrazone types of ligands namely, acetylacetone- 2-hydroxyphenylhydrazone (APAcAc), acetoacetanilide- 2-hydroxyphenylhydrazone (APAcAcA) and acetoacetanilide-3,5-dihydro-2,4-dione pyrimidylhydrazone (AUAcAcA) were synthesized by diazotization of primary amine and coupling with compounds containing active methylene group. First part of the thesis deals with the synthesis of Fe, Co, Ni and Cu complexes using three hydrazone types of ligands are given. Details regarding the characterization of these complexes with a view to establishing the molecular structures are presented in this part. The other part contains the method of encapsulation of these complexes in zeolite cavities and their characterizations of the encapsulated metal species are described. A comparitive account of the catalytic activities of the pure and encapsulated complexes for cyclohexanol oxidation was also carried out.

Diversity in Structural and Spectural Characteristics of Some Transition Metal Complexes Derived From Aldehyde Based Thiosemicarbazone Ligands

The study deals with the diversity in structural and spectural characteristics of some transition metal complexes derived from aldehyde based thiosemicarbazone ligands thiosemicarbazones are a family of compounds with beneficial biological activity viz., anticancer,antitumour, antifungal, antibacterial, antimalarial, antifilarial, antiviral and anti-HIV activities. Many thiosemicarbazone ligands and their complexes have been prepared and screened for their antimicrobial activity against various types of fungi and bacteria. The results prove that the compounds exhibit antimicrobial properties and it is important to note that in some cases metal chelates show more inhibitory effects than the parent ligands. The increased lipophilicity of these complexes seems to be responsible for their enhanced biological potency. Adverse biological activities of thiosemicarbazones have been widely studied in rats and in other species. The parameters measured show that copper complexes caused considerable oxidative stress and zinc zinc complexes behaved as antioxidants. It has applications on analytical field also. Some thiosemicarbazones produce highly colored complexes with metal ions. This thesis aims to synthesis some novel thiosemicarbazone ligands and their transition metal complexes together with their physico-chemical characterization.

Fabrication Of Potentiometric Sensors For The Determination Of Certain Metal Ions

In this study Fabrication of Potentiometric sensors for the determination of certain metal ions, presents the synthesis and characterization of seven ionophores, their use in the fabrication of potentiometric sensors and the results and discussion of fourteen sensors developed for the determination of five transition metal ions. As part of the present investigations a total of fourteen potentiometric sensors have been developed and fabricated. A three fold approach has been taken in developing he sensors, PVC plasticized membrane sensor, carbon paste electrode and chemically modified carbon paste electrode. All the sensors are highly useful in the determination of metal ions such as manganese, nickel, copper, mercury and lead. A through analytical study has been carried out with respect to each other developed. Based on these studies, optimum conditions have been developed for the quantitative determinations of the selected metal ions using the sensors. Systematic application studies have also been carried out for all the developed sensors and the results revealed that the presently developed sensors are far superior than most of the sensors reported.

Growth and Characterization of ZnO based Heterojunction diodes and ZnO Nanostructuresby Pulsed Laser Ablation

Transparent conducting oxides (TCO’s) have been known and used for technologically important applications for more than 50 years. The oxide materials such as In2O3, SnO2 and impurity doped SnO2: Sb, SnO2: F and In2O3: Sn (indium tin oxide) were primarily used as TCO’s. Indium based oxides had been widely used as TCO’s for the past few decades. But the current increase in the cost of indium and scarcity of this material created the difficulty in obtaining low cost TCO’s. Hence the search for alternative TCO material has been a topic of active research for the last few decades. This resulted in the development of various binary and ternary compounds. But the advantages of using binary oxides are the easiness to control the composition and deposition parameters. ZnO has been identified as the one of the promising candidate for transparent electronic applications owing to its exciting optoelectronic properties. Some optoelectronics applications of ZnO overlap with that of GaN, another wide band gap semiconductor which is widely used for the production of green, blue-violet and white light emitting devices. However ZnO has some advantages over GaN among which are the availability of fairly high quality ZnO bulk single crystals and large excitonic binding energy. ZnO also has much simpler crystal-growth technology, resulting in a potentially lower cost for ZnO based devices. Most of the TCO’s are n-type semiconductors and are utilized as transparent electrodes in variety of commercial applications such as photovoltaics, electrochromic windows, flat panel displays. TCO’s provide a great potential for realizing diverse range of active functions, novel functions can be integrated into the materials according to the requirement. However the application of TCO’s has been restricted to transparent electrodes, ii notwithstanding the fact that TCO’s are n-type semiconductors. The basic reason is the lack of p-type TCO, many of the active functions in semiconductor originate from the nature of pn-junction. In 1997, H. Kawazoe et al reported the CuAlO2 as the first p-type TCO along with the chemical design concept for the exploration of other p-type TCO’s. This has led to the fabrication of all transparent diode and transistors. Fabrication of nanostructures of TCO has been a focus of an ever-increasing number of researchers world wide, mainly due to their unique optical and electronic properties which makes them ideal for a wide spectrum of applications ranging from flexible displays, quantum well lasers to in vivo biological imaging and therapeutic agents. ZnO is a highly multifunctional material system with highly promising application potential for UV light emitting diodes, diode lasers, sensors, etc. ZnO nanocrystals and nanorods doped with transition metal impurities have also attracted great interest, recently, for their spin-electronic applications This thesis summarizes the results on the growth and characterization of ZnO based diodes and nanostructures by pulsed laser ablation. Various ZnO based heterojunction diodes have been fabricated using pulsed laser deposition (PLD) and their electrical characteristics were interpreted using existing models. Pulsed laser ablation has been employed to fabricate ZnO quantum dots, ZnO nanorods and ZnMgO/ZnO multiple quantum well structures with the aim of studying the luminescent properties.