Mohammed Yusuff, K K; Digna, Varghese; Arun, Vasudevan; Robinson, P P; Manju, Sebastian; Leeju, P; Varsha, Gopalakrishnan(International Union of Crystallography, Acta Crystallographica Section C ,Crystal Structure Communications, November 11, 2009)
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Abstract:
The Schiff base compounds N,N0-bis[(E)-quinoxalin-2-ylmethylidene]
propane-1,3-diamine, C21H18N6, (I), and N,N0-bis[(E)-
quinoxalin-2-ylmethylidene]butane-1,4-diamine, C22H20N6,
(II), crystallize in the monoclinic crystal system. These
molecules have crystallographically imposed symmetry.
Compound (I) is located on a crystallographic twofold axis
and (II) is located on an inversion centre. The molecular
conformations of these crystal structures are stabilized by
aromatic pye stacking interactions.
Mohammed Yusuff, K K; Manju, Sebastian; Arun, Vasudevan; Robinson, P P; Leeju, Pally; Digna, Varghese; Varsha, Gopalakrishnan(Taylor & Francis, Journal of Coordination Chemistry, October 15, 2009)
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Abstract:
The mononuclear cobalt(II) complex [CoL2] H2O (where HL is quinoxaline-2-carboxalidine-
2-amino-5-methylphenol) has been prepared and characterized by elemental analysis, conductivity
measurement, IR, UV-Vis spectroscopy, TG-DTA, and X-ray structure determination.
The crystallographic study shows that cobalt(II) is distorted octahedral with each tridentate
NNO Schiff base in a cis arrangement. The crystal exhibits a 2-D polymeric structure parallel to
[010] plane, formed by O-H...N and O-H... O intermolecular hydrogen bonds and pye
stacking interactions, as a racemic mixture of optical enantiomers. The ligand is a Schiff base
derived from quinoxaline-2-carboxaldehyde
Mohammed Yusuff, k K; Varsha, Gopalakrishnan; Arun, Vasudevan; Manju, Sebastian; Leeju, P; Digna, Varghese(Crystallography Journals,Acta Crystallographica Section E ,Structure Reports, March 24, 2009)
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Abstract:
The asymmetric unit of the title compound, C11H8N4, contains
two independent molecules. In the crystal structure, intermolecular
N—H.....N hydrogen bonds link molecules into
ribbons extended in the [100] direction
Mohammed Yusuff, K K; Digna, Varghese; Arun, Vasudevan; Manju, Sebastian; Leeju, P; varsha, Gopalakrishnan(Crystallography Journals,Acta Crystallographica Section E ,Structure Reports, January 23, 2009)
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Abstract:
In the molecule of the title compound, C20H16N6, the central
C—C bond lies on a crystallographic inversion centre. The
quinoxalidine ring is nearly planar, with a maximum deviation
of 0.021 (2) A ˚ from the mean plane. The crystal structure is
stabilized by intermolecular C—H....N interactions, leading to
the formation of a layer-like structure, which extends along the
a axis
Girish Kumar, K; Joseph, Renjini(Taylor & Francis, June 1, 2009)
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Abstract:
A metalloporphyrin incorporated carbon paste sensor has been developed
for the determination of metronidazole benzoate (MTZB). Zn(II) complex
of 5,10,15,20-tetrakis (3-methoxy-4-hydroxy phenyl) porphyrin (TMHPP) was
used as the active material. The MTZB gave a well-defined reduction peak at
- 0.713V in 0.1 mol l -1 phosphate buffer solution of pH around 7. Compared
with bare carbon paste electrode (CPE), the TMHPP Zn(II) modified electrode
significantly enhanced the reduction peak current of MTZB as well as lowered
its reduction potential. Under optimum conditions the reduction peak current
was proportional to MTZB concentration over the range 1×10-3 mol1-1 to 1×10-5mol1-1. The detection limit was found to be 4.36×10-6mol1-1
. This
sensor has been successfully applied for the determination of MTZB in pharmaceutical
formulations and urine samples.
Mohammed Yusuff, K K; Arun, Vasudevan; Robinson, P P; Manju, Sebastian; Leeju, P; Varsha, Gopalakrishnan; Digna, Vasudevan(Elsevier, Dyes and Pigments 82 (2009) 268–275, January 18, 2009)
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Abstract:
A novel bisazomethine Schiff base was synthesised by the condensation of 3-hydroxyquinoxaline-2-
carboxaldehyde and 2,3-diaminomaleonitrile. 1H NMR, 13C NMR, HPLC and FT-IR studies revealed that
the compound exists in two major tautomeric forms. The Schiff base exhibits positive absorption and
fluorescent solvatochromism and displays dual fluorescence with large stoke shifts. Cyclic voltammetric
analysis of the compound in 1:1 methanol–THF was influenced by scan rate. Thermal analysis of the
compound was undertaken using TG–DTA and DSC
Mohammed Yusuff, K K; Arun, Vasudevan; Sreedevi, N; Robinson, P P; Manju, Sebastian(Elsevier,Journal of Molecular Catalysis A: Chemical 304 (2009) 191–198, February 7, 2009)
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Abstract:
Two new complexes, [MII(L)(Cl)(H2O)2]·H2O (where M=Ni or Ru and L = heterocyclic Schiff base, 3-
hydroxyquinoxaline-2-carboxalidene-4-aminoantipyrine), have been synthesized and characterized by
elemental analysis, FT-IR, UV–vis diffuse reflectance spectroscopy, FAB-MASS, TG–DTA, AAS, cyclic
voltammetry, conductance and magnetic susceptibility measurements. The complexes have a distorted
octahedral structure andwere found to be effective catalysts for the hydrogenation of benzene. The influence
of several reaction parameters such as reaction time, temperature, hydrogen pressure, concentration
of the catalyst and concentration of benzenewas tested. A turnover frequency of 5372 h−1 has been found
in the case of ruthenium complex for the reduction of benzene at 80 ◦C with 3.64×10−6 mol catalyst,
0.34 mol benzene and at a hydrogen pressure of 50 bar. In the case of the nickel complex, a turnover
frequency of 1718 h−1 has been found for the same reaction with 3.95×10−6 mol catalyst under similar
experimental conditions. The nickel complex shows more selectivity for the formation of cyclohexene
while the ruthenium complex is more selective for the formation of cyclohexane
Deepu, V; Dr. Mohanan, P(Cochin University of Science & Technology, April , 2009)
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Abstract:
Antennas are indispensable component of any wireless communication
device. An antenna is a transducer between the transmitter
and the free space waves and vice versa. They efficiently transfer
electromagnetic energy from a transmission line into free space.
But the present day communication applications require compact and ultra wide band designs which cannot be catered by simple microstrip based designs. PIFAs have solved the
problem to some extend, but the field of antennas needs more innovative designs
In this thesis the design and development of compact planner antenna are
presented. Emphasis is given to the design of the feed as well as the radiator
resulting in simple compact uniplanar geometries. The Asymmetric coplanar
feed used to excite the antennas is found to be a suitable choice for feeding compact antennas.The main objectives of the study are the design of compact single, dual and multi band antennas with uniplanar
structure and extension of the design for practical GSM/WLAN
applications and Ultra compact antennas using the above techniques and
extension of the design to antennas for practical applications like
RFID/DVB-H. All the above objectives are thoroughly studied. Antennas with ultra
compact dimensions are obtained as a result of the study. Simple equations are
provided to design antennas with the required characteristics. The design equations are verified by designing different antennas for different applications.
Description:
Department of Electronics, 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