Spectral and Structural Studies of Transition Metal Complexes of Thiosemicarbazones Containing Ring Incorporated at N(4)-position

The thesis is an introduction to evaluate the coordination behaviour of a few compounds of our interest. The crucial aim of these investigations was to synthesize and characterize some transition metal complexes using the ligands benzaldehyde, 2-hydroxybenzaldehyde and 4-methoxybenzaldehyde N(4)-ring incorporated thiosemicarbazones.The study involves a brief foreword of the metal complexes of thiosemicarbazones including their bonding, stereochemistry and biological activities.The different analytical and spectroscopic techniques used for the analysis of the ligands and their complexes are discussed.It also deals with the synthesis and spectral characterization of the thiosemicarbazones and single crystal X-ray diffraction study of one of them.Chapter 3 describes the synthesis, spectral characterization, single crystal X-ray diffraction studies of copper(ll) complexes with ONS/NS donor thiosemicarbazones. Chapter 4 deals with the synthesis, spectral characterization and single crystal X-ray diffraction studies of nickel(II) complexes. Chapter 5 contains the synthesis, structural and spectral characterization of the cobalt(III) complexes. Chapters 6 and 7 include the synthesis, structural and spectral characterization of zinc(II) and cadmium(ll) complexes with ONS/NS donor thiosemicarbazones.

The ligating versatility of halides and pseudohalides in copper(II) complexes- monomers, dimers and chains”

The work embodied in this thesis was carried out by the author in the Department of Applied Chemistry, CUSAT, Kochi, during the period 2008-2013. The thesis brings to light, our attempts to evaluate the coordination behavior of some compounds of interest. The biological activities of semicarbazones and their metal complexes have been an active area of research during the past years because of their significant role in naturally occurring biological systems. Tridentate NNO and ONO semicarbazone systems formed from heterocyclic and aromatic carbonyl compounds and their transition metal complexes are well-authenticated compounds in this field and their synthesis, crystal structures and spectral studies are well desirable. Hence, we decided to develop a research program aimed at the syntheses, crystal structures and spectral studies of copper complexes with halides and pseudohalides. In addition to single crystal X-ray diffraction studies, various physico-chemical methods of analysis were also used for the characterization of the complexes

Mono- and binuclear transition metal complexes of n(4)-substituted thiosel\licarbazones derived frol\i salicylaldehyde and 2-hydroxyacetophenone synthesis, spectral and structural studies

The work embodied in the thesis is divided into eight chapters. Chapter I gives a brief introduction about metal complexes of thiosemicarbazones, including their structural and bonding properties. Chapter 2 deals with the synthesis and single crystal X-ray diffraction studies of various thiosemicarbazones used up for the present investigations and various characterization techniques. Chapter 3 deals with synthesis, spectral and structural studies of Cu(U) complexes with ONS donor thiosemicarbazones. Chapter 4 deals with synthesis and spectral studies of Ni(II) complexes \vith 2-hydroxyacetophenone N(4)-cyclohexyl thiosemicarbazone as the ligand. Chapter 5 includes synthesis and spectral studies of Mn(II) complexes. Chapter 6 deals with synthesis, spectral and structural studies of Zn(II) complexes. Chapter 7 includes synthesis and spectral studies of oxovanadium(IV) complexes. Chapter 8 deals with synthesis, spectral and single crystal X-ray diffraction studies of dioxomolybdenum(VI) complexes.

Formation of an unusual copper(II) complex from the degradation of a novel tricopper(II) carbohydrazone complex

An unusual copper(II) complex [Cu(L1a)2Cl2] CH3OH H2O H3O+Cl (1a) was isolated from a solution of a novel tricopper(II) complex [Cu3(HL1)Cl2]Cl3 2H2O (1) in methanol, where L1a is 3-(2-pyridyl)triazolo [1,5-a]-pyridine, and characterized with single crystal X-ray diffraction study. The tricopper(II) complex of potential ligand 1,5-bis(di-2-pyridyl ketone) carbohydrazone (H2L1) was synthesized and physicochemically characterized, while the formation of the complex 1a was followed by time-dependant monitoring of the UV–visible spectra, which reveals degradation of ligand backbone as intensity loss of bands corresponding to O?Cu(II) charge transfer

Synthesis, spectral and structural studies of novel binuclear Ni(II) complex of salicylaldehyde 3-azacyclothiosemicarbazone

A novel binuclear Ni(II) complex of salicylaldehyde 3-azacyclothiosemicarbazone (H2L) has been synthesized and characterized by elemental analysis, IR and UV–Vis spectroscopy. The single crystal X-ray structure of the complex shows that bridging occurs through thiolato sulfur and phenolic oxygen atoms. Nickel centers in the complex have square planar and octahedral geometries

(E)-2-(4-Benzyloxy-2-hydroxybenzylidene)- N-phenylhydrazinecarbothioamide

The title compound, C21H19N3O2S, exists in the thione form. The configuration about the C N bond is E. The hydrazinecarbothioamide unit adopts an almost planar arrangement, with maximum deviations of 0.016 (3) and 0.016 (2) A ° for the two thiourea N atoms. An intramolecular O—H N hydrogen bond occurs. Weak intermolecular N— H S, C—H O and C—H interactions are observed in the crystal structure

Nucleophilic addition of Nitrones to Electron deficient acetylenes and related studies

Nitrones or azomethine-N-oxides are important precursors for the synthesis of several heterocyclic systems. They belong to the allyl anion type 1,3-dipoles and possess unique structural features which make them extraordinarily useful synthons. They behave as 1,3-dipoles in 1,3-dipolar cycloaddition reactions and as electrophiles in reactions with organometallic reagents. These are the two basic reactions given by nitrones. Nitrones also act as ‘spin traps’ in which they react with short-lived radicals to furnish stable nitroxide radicals which can be detected and identified by electron paramagnetic resonance (EPR) spectroscopy. Recently SmI2 catalysed reductive cross-coupling reactions of nitrones have gained significant interest in which the reactions are initiated by single electron transfer (SET) to nitrones. Apart from these reactions, nitrones are also known to participate in reactions which are initiated by the nucleophilic attack of nitrone-oxygen. In our group, we have also explored the nucleophilic character of nitrones through various reactions. The results obtained enabled us to develop a novel two-step one-pot strategy for quinolines and indoles - the heterocycles renowned for their pharmacological applications, from nitrones and electron deficient acetylenes. Using dibenzoylacetylene and phenylbenzoylacetylene as dipolarophiles, we could introduce a desired functional group at a predetermined position of the quinolines or indoles to be synthesised. In this context, the thesis entitled “NUCLEOPHILIC ADDITION OF NITRONES TO ELECTRON DEFICIENT ACETYLENES AND RELATED STUDIES” portrays our attempt to expand the scope of our x novel synthetic protocol using ester functionalised acetylenes: dimethyl acetylenedicarboxylate (DMAD) and methyl propiolate. The thesis is organised in to five chapters. The first chapter briefly describes the different classes of reactions that nitrone functionality can tolerate. The research problem is defined at the end of this chapter. The second chapter describes the synthesis of different nitrones used for the present study. The optimisation and expansion of scope of the novel strategy towards quinoline synthesis is discussed in the third chapter. The fourth chapter portrays the synthesis of indole-3-carboxylates using the novel strategy. In the fifth chapter, the reaction of N-(2,6-dimethylphenyl) and N-(2,4,6-trimethylphenyl)nitrones are discussed. Here we also discuss the mechanistic reinvestigation of Baldwin’s proposal in the isoxazoline-oxazoline rearrangement. The major outcome of the work is given at the end of the thesis. The structural formulae, schemes, tables and figures are numbered chapter-wise since each chapter of the thesis is organized as an independent unit. All new compounds (except two compounds reported in fourth chapter) are fully characterised on the basis of spectral and analytical data and single crystal X-ray analysis on representative examples. Relevant references are included at the end of individual chapters.

Infrared and polarized Raman spectra of Cu(HSeO3)2 • H20 single crystal

Infrared and polarized Raman spectra of Cu(HSeO3) 2 - H20 single crystal have been recorded and analysed. The appearance of non-degenerate Se-OH stretching vibrations in the ~x: and ~y: polarizations of Raman spectra indicate distortion of the HSeO~- ion in the Cu(HSeO3)2 - H20 crystal. The low wavenumber values obtained for the symmetric and asymmetric stretching vibrations of the HSeO 3 ion are consistent with the strong hydrogen bonding and the influence of Jahn-Teller distortion as predicted in X-ray diffraction data. The shifting of the stretching and bending vibrations of the hydroxyl groups and water molecules from the free state values also confirms the strong hydrogen bonding in this crystal. Broad bands observed for both stretching and bending regions become sharp in the Raman spectrum recorded at 77 K. A doublet appears for the Se-OH stretching mode at this temperature indicating the settling of protons in an ordered position and the absence of intrabond proton tunnelling

X-Ray Crysatllographic and Vibrational Spectroscopic Studies of Thorium Bromate Hydrate

Th(BrO3)3·H2O single crystals were grown from its aqueous solution at room temperature. Single crystal XRD, Raman and FTIR techniques were used to investigate the crystal structure. The crystal structure was solved by Patterson method. The as grown crystals are in monoclinic system with space group P21/c. The unit cell parameters are a = 12.8555(18) Å, b = 7.8970(11) Å, c = 9.0716(10) Å,  = 90°,  = 131.568° and  = 90° and unit cell volume is 689.1(2) Å3. Z = 8, R factor is 5.9. The Raman and FTIR studies indicate the lowering of symmetry of bromate anion from C3V to C1. Hydrogen bonds with varying strengths are present in the crystal. The centrosymmetric space group P21/c of the crystal is confirmed by the non-coincidence of majority of Raman and IR bands

Investigations on some amino acid based single crystals for nonlinear optical applications and amino acid capped nanocrystals

Organic crystals possess extremely large optical nonlinearity compared to inorganic crystals. Also organic compounds have the amenability for synthesis and scope for introducing desirable characteristics by inclusions. A wide variety of organic materials having electron donor and acceptor groups, generate high order of nonlinearity. In the present work, a new nonlinear optical crystal, L-citrulline oxalate (LCO) based on the aminoacid L-citrulline was grown using slow evaporation technique. Structural characterization was carried out by single crystal XRD. It crystallizes in the noncentrosymmetric, orthorhombic structure with space group P21 P21 P21. Functional groups present in the sample were identified by Fourier transform infra red (FTIR) and FT-Raman spectral analysis. On studying the FTIR and Raman spectra of the precursors L-citrulline and oxalic acid, used for growing L-citrulline oxalate crystal, it is found that the significant peaks of the precursors are present in the spectra of the L-citrulline oxalate crystal . This observation along with the presence of NH3 + group in the spectra of L-citrulline oxalate, confirms the formation of the charge transfer complex

Effect of Ce3+ Ion on the X-Ray Induced Fluorescence Emission from CaS

The effect of Ce3+ on the fluorescence emission from CaS:Ce3+ phosphor is studied using X-ray excitation. Apart from the emission in the visible region, the phosphor also shows fluorescence emission in the ultraviolet region. Variation in wavelengths and intensities of these emissions due to change in dopant concentration is also analysed.

Studies an Optical and X-ray Emission Processes in Laser Produced Plasma

Developments in laser technology over the past few years have made it possible to do experiments with focused intensities of IO"-102' Wcm'z. Short-pulse high-intensity lasers are able to accelerate protons and heavier ions to multi-MeV energies during their interaction with solid targets, gas jets and clusters. When such a laser radiation is focused at the intensity above 10” Wcm'2, local electric field strength will be almost equivalent to that within an atom. Hence, new nonlinear optical phenomena will be expected in the field of light matter interaction. Most of the research in the material interaction using high power lasers, especially related to plasma interaction, has been directed to the short pulse x-ray generation- Nanosecond laser interactions with solid targets also generate plasmas which emit radiation mainly in the optical region, the understanding of which is far from satisfactory. This thesis deals with a detailed study of some of the dynamical processes in plasmas generated by nanosecond and femtosecond lasers

Temperature dependent polarized Raman spectra of nonaaqualanthanoid (Pr) single crystal

Polarized Raman spectral changes with respect to temperature were investigated for Pr(BrO3)3·9H2O single crystals. FTIR spectra of hydrated and deuterated analogues were also recorded and analysed. Temperature dependent Raman spectral variation have been explained with the help of the thermograms recorded for the crystal. Factor group analysis could propose the appearance ofBrO3 ions at sites corresponding to C3v (4) and D3h (2). Analysis of the vibrational bands at room temperature confirms a distorted C3v symmetry for the BrO3 ion in the crystal. From the vibrations of water molecules, hydrogen bonds of varying strengths have also been identified in the crystal. The appearance υ1 mode of BrO3− anion at lower wavenumber region is attributed to the attachment of hydrogen atoms to the BrO3− anion. At high temperatures, structural rearrangement is taking place for bothH2Omolecule and BrO3 ions leading to the loss ofwater molecules and structural reorientation of bromate ions causing phase transition of the crystal at the temperature of 447 K.