Suni, V; Dr.Prathapachandra Kurup,M R(Cochin University of Science and Technology, August 29, 2005)
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Abstract:
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.
Description:
Department of Applied Chemistry,Cochin University of Science and Technology
Leji, Latheef; Dr.Prathapachandra Kurup,M R(Cochin University of Science & Technology, September , 2007)
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Abstract:
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.
Description:
Department of Applied Chemistry,
Cochin University of Science and Technology
Varughese,Philip; Prathapachandra Kurup, M R(Dept. of Applied Chemistry, July , 2004)
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Abstract:
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.
Sivakumar,S; Prathapachandra Kurup, M R(Department of Applied Chemistry, 2002)
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Abstract:
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.
Sivakumar,S; Prathapachandra Kurup, M R(Department of Applied Chemistry, 2002)
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Abstract:
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
Renjusha, S; Dr.Prathapachandra Kurup,M R(Cochin University of Science and Technology, April , 2012)
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Abstract:
Thiosemicarbazones have recently attracted considerable attention due to
their ability to form tridentate chelates with transition metal ions through either
two nitrogen and sulfur atoms, N–N–S or oxygen, nitrogen and sulfur atoms,
O–N–S. Considerable interest in thiosemicarbazones and their transition metal
complexes has also grown in the areas of biology and chemistry due to
biological activities such as antitumoral, fungicidal, bactericidal, antiviral and
nonlinear optical properties. They have been used for metal analyses, for
device applications related to telecommunications, optical computing, storage
and information processing.The versatile applications of metal complexes of thiosemicarbazones in various fields prompted us to synthesize the tridentate NNS-donor
thiosemicarbazones and their metal complexes. As a part of our studies on
transition metal complexes with these ligands, the researcher undertook the current work
with the following objectives.
1. To synthesize and physico-chemically characterize the following
thiosemicarbazone ligands:
a. Di-2-pyridyl ketone-N(4)-methyl thiosemicarbazone (HDpyMeTsc)
b. Di-2-pyridyl ketone-N(4)-ethyl thiosemicarbazone (HDpyETsc)
2. To synthesize oxovanadium(IV), manganese(II), nickel(II), copper(II),
zinc(II) and cadmium(II) complexes using the synthesized
thiosemicarbazones as principal ligands and some anionic coligands.
3. To study the coordination modes of the ligands in metal complexes by
using different physicochemical methods like partial elemental analysis,
thermogravimetry and by different spectroscopic techniques.
4. To establish the structure of compounds by single crystal XRD studies
Description:
Department of Applied Chemistry, Cochin University of Science and Technology