Leeju, P; Dr.Mohammed Yusuff,K K(Cochin University of Science & Technology, April , 2011)
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Abstract:
In this thesis we report the synthsis and characterisation of new transition metal complexes of Pd(II),Cu(II),Ru(II) and Ir(III) of Schiff bases derived from quinoxaline-2-carboxaldehyde/3-hydroxyquinoxaline-2-carboxaldehyde and 5-aminoindazole.6-aminoindazole or 8-aminoquinoline.The complexes have been characterised by spectral and analytical data.Pd(II) and Cu(II) form square planar complexes and Ru(III) and Ir(III) form ctahedral complexes with these Schiff bases.The DNA binding properties of theses synthesised complexes have been studied by various methods including electronic absoption spectroscopy,cyclic voltammetry,different pulse voltammetry and circular dichroism spectra were used.Gel electrophoresis experiments were also performed to investigate the DNA cleavage of theses complexes.Furthermore Ru(III) and Ir(III) complexes find application as oxidation and hydogenation catalsts. The studies on catalytic activities has been presented.The metal complexes presented in this thesis assure significance as they contribute to the development of new DNA binding agents and antibacterial and anticancer drugs.
Description:
Dept.of Applied Chemistry,Cochin University of Science and Technology
Digna, Varghese; Dr.Mohammed Yusuff,K K; Dr.Unnikrishnan, P A(Cochin University of Science & Technology, August , 2011)
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Abstract:
This thesis is mainly concerned with the synthesis and characterisation of new simple and zeolite encapsulated transition metal (manganese(II),nickel(II),and copper(II)complexes of quinoxaline based double Schiff base ligands.Theses ligands are N,N'-bis(quinoxaline-2-carboxalidene)hydrazine,N,N'-bis(quinoxaline-2-carboxalidene)-1,2-diaminoethane,N,N'-bis(quinoxaline-2-carboxalidene)-1,3-diamonopropane,N,N'-bis(quinoxaline-2-carboxalidene)-1,4-diaminobutane,N,N'-bis(quinoxaline-2-carboxalidene)-1,2-diaminocyclohexane and N,N'-bis(quinoxaline-2-carboxalidene)-1,2-diaminobenzene.The Schiff base ligands have been characterised by spectral and single crystal XRD studies.Theses ligands provide great structural diversity during complexation.Mn(II) and Ni(II) form octahedral with these Schiff bases,whereas Cu(II) forms both octahedral and tetrahedral complexes.Studies on the biological and Catalytic activity of the copper(ll) complexes are also presented in this thesis.
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Dept.of Applied Chemistry,Cochin University of Science and Technology
Varsha, G; Dr.Mohammed Yusuff,K K(Cochin University of Science and Technology, May , 2011)
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Abstract:
Schiff base complexes of transition metal ions have played a significant role in coordination chemistry.In the present study we have synthesized some new Mn(II),Co(II) and Cu(II) complexes of Schiff bases derived from 1,8-diaminonaphthalene.Even though we could not isolate theses Schiff bases (as they readily cyclise to form the perimidine compounds),we were able to characterize unequivacally the complexes synthesized from these compounds as complexes of Schiff Bases. We Synthesized three perimidine derivatives ,2-(quinoxalin-2-yl)-2,3-dihydro-1H-perimidine,2-(2,3-dihydro-1H-perimidin-2-yl)-6-methoxyphenol and 4-(2,3-dihyro-1H-perimidin-2-yl)-2-methoxyphenol by the condensation of 1,8-diaminonaphthalene with quinoxaline-2-carboxaldehyde,2- hydroxy-3-methoxybenzaldehyde or 4-hydroxy-3-methoxybenzaldehyde respectively.Theses compounds were used as precursor ligands for the preparation of Schiff base complexes.The complexes were characterized by using elemental analysis ,conductance and magnetic susceptibility measuremets ,infrared and UV-Visible spectroscopy ,thermogravimetric analysis and EPR spectroscopy .We also encapsulated the complexes in zeolite Y matrix and these encapsulated complexes were also characterized. We have also tried theses complexes as catalysts in the oxidation of cyclohexanol and decomposition of hydrogen peroxide.
Description:
Dept.of Applied Chemistry,Cochin University of Science and Technology
Pearly Sebastian, Chittilappilly; Mohammed Yusuff, K K(Cochin University of Science and Technology, March , 2007)
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Abstract:
In the present study an attempt has been made to synthesize some simple complexes of
multidentate ligands. Analogous zeolite encapsulated complexes were also synthesized and
characterized. Immobilization on to polymer supports through covalent attachment is
expected to solve the problem of decomposition of many complexes during catalytic reaction.
Hence the work is also extended to the synthesis and characterization of some polymer
supported complexes of Schiff base Iigands. All the three types of synthesized complexes,
simple, zeolite encapsulated and polystyrene anchored, were subjected to catalytic activity
study towards catechol-oxidation reaction. A selected group of complexes were also screened
for their catalytic activity towards phenol-oxidation reaction. Biological screening of the
synthesized ligands and neat complexes were done with a view to establish the effect of
complexation on biological systems.
Description:
Department of Applied Chemistry,
Cochin University of Science and Technology
Arun,V; Dr.Mohammed Yusuff,K K(Cochin University of Science & Technology, June , 2009)
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Abstract:
The thesis deals with studies on the synthesis, characterisation and catalytic
applications of some new transition metal complexes of the Schiff bases derived from 3-hydroxyquinoxaline 2-carboxaldehyde.. Schiff bases which are considered as ‘privileged ligands’ have the ability to stabilize different metals in different oxidation states and thus regulate the performance of metals in a large variety of catalytic transformations. The
catalytic activity of the Schiff base complexes is highly dependant on the environment about
the metal center and their conformational flexibility. Therefore it is to be expected that the
introduction of bulky substituents near the coordination sites might lead to low symmetry complexes with enhanced catalytic properties. With this view new transition metal
complexes of Schiff bases derived from 3-hydroxyquinoxaline-2-carboxaldehyde have been
synthesised. These Schiff bases have more basic donor nitrogen atoms and the presence of
the quinoxaline ring may be presumed to build a favourable topography and electronic
environment in the immediate coordination sphere of the metal. The aldehyde was condensed
with amines 1,8-diaminonaphthalene, 2,3-diaminomaleonitrile, 1,2-diaminocyclohexane,
2-aminophenol and 4-aminoantipyrine to give the respective Schiff bases. The oxovanadium(IV), copper(II) and ruthenium(II)complexes of these Schiff bases were synthesised and characterised.
All the oxovanadium(IV) complexes have binuclear structure with a square pyramidal geometry.
Ruthenium and copper form mononuclear complexes with the Schiff base derived from 4-
aminoantipyrine while binuclear square planar complexes are formed with the other Schiff
bases. The catalytic activity of the copper complexes was evaluated in the hydroxylation of
phenol with hydrogen peroxide as oxidant. Catechol and hydroquinone are the major products. Catalytic properties of the oxovanadium(IV) complexes were evaluated in the
oxidation of cyclohexene with hydrogen peroxide as the oxidant. Here allylic oxidation
products rather than epoxides are formed as the major products. The ruthenium(II)
complexes are found to be effective catalysts for the hydrogenation of benzene and toluene.
The kinetics of hydrogenation was studied and a suitable mechanism has been proposed.
Description:
Department of Applied Chemistry, Cochin
University of Science and Technology
Manju, Sebastian; Dr.Mohammed Yusuff,K K(Cochin University of Science & Technology, July , 2010)
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Abstract:
Schiff base complexes of transition metal ions have played a significant role in coordination chemistry.The convenient route of synthesis and thermal stability of Schiff base complexes have contributed significantly for their possible applications in catalysis,biology,medicine and photonics.Significant variations in cataltytic activity with structure and type are observed for these complexes.The thesis deals with synthsis and characterization of transition metal complexes of quinoxaline based Schiff base ligands and their catalytic activity study.The Schiff bases synthesized in the present study are quinoxaline-2-carboxalidine-2-amino-5-methylphenol,3-hydroxyquinoxaline-2-carboxalidine-2-amino-5-methylphenol,quinoxaline-2-aminothiophenol.They provide great structural diversity during complexation.To the best of our knowledge, the transition metal complexes of quinoxaline based Schiff bases are poorly utilised in academic and industrial research.
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Dept.of Applied Chemistry,Cochin University of Science and Technology
Sreesha, Sasi; Dr.Prathapachandra Kurup,M R(Cochin University of Science & Technology, October , 2008)
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Abstract:
Metallo-organic chemistry,incorporating the frontiers of both inorganic and organic chemical aspects,is a topic of utility concern.The first exploration of coordinated metal complexes dates back to the ninettenth century,during the days of Alfred Werner.Thereafter,inorganic chemistry witnessed a great outflow of coordination compounds,with unique structural characteristics and diverse applicatons.The diversity in structures exhibited by the coordination complexes of multidentate ligands have led to their usage as sensors,models for enzyme mimetic centers,medicines etc.The liganda chosen are of prime importance in determining the properties of coordination compounds.Schiff bases are compounds obtained by the condensation of an aidehyde or ketone with an amine.The chemical properties of Schiff bases and their complexes are widely explored in recent years owing to their pharmacological activity,their catalytic activities and so on.On the other hand pseudohalides like azide and thiocyanate are versatile candidates for the construction of dimeric or polymeric complexes having excellent properties and diverse applications.So a combination of the Schiff bases and the pseudohalogens for the synthesis of metal complexes can bring about interesting results.An attempt into this area is the besis of this Ph.D theis.
Description:
Department of Applied Chemistry,
Cochln University of Science and Technology