Browsing by Author "Kumari Bindu"

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Pentacoordinated Cu(II)/Zn(II) complexes bearing macrocyclic skeleton: Synthesis, spectroscopic and molecular structure optimization studies
(2005) Lallan Mishra; Kumari Bindu; Subrato Bhattacharya
2,6-Diacetylpyridine and 1,2-diaminoethane in the presence of copper(II) and zinc(II) chlorides containing a few drops of acetic acid were condensed into compositions [CuLH2]2·2HCl·H2O (1), [Cu2LPyz]2·2HCl·4CH 3COCH3 (2) [CuZnLPyz]2·2HCl· 2CH3COCH3·10H2O (3) and [ZnL'Cl] 3·3HCl·3H2O (4) substantiated by elemental analyses, IR, UV-vis, 1H NMR and FAB mass spectral data. Demetallation of a Ni(II) complex (isolated as above) afforded macrocyclic skeleton LH4, whereas L' symbolizes a skeleton of the ligand containing only ethylenediamine and 2,6-diacetylpyridine. Molecular structure optimization using MM2 force field calculations for the complexes revealed distorted square pyramidal geometry around Cu(II) centers in complexes 1 and 2 and tetrahedral geometry around Cu(II) and Zn(II) centers with different degrees of distortion in complex 3 whereas three Zn(II) atoms (each in distorted square pyramidal geometry) attached via Cl bridges form a cyclic structure in complex 4. In complexes 1 and 2,Cu-Cu = 2.63-2.66 Å indicated the possibility of coupling between the two Cu(II) centers which has been supported by lower magnetic moment as well as ESR spectra showing half-field signal. © 2004 Elsevier B.V. All rights reserved.
Some novel facets of copper-zinc superoxide dismutase
(Indian Chemical Society, 2003) Lallan Mishra; Kumari Bindu
This review introduces the field of superoxide dismutase research especially about copper-zinc superoxide dismutase. Attempts have been made to present the current status of synthetic metal complexes which could be exploited as models of superoxide dismutase. We have compared our findings in this area with the reported data.
Spectroscopic studies, structure simulation and phenol binding property of dimetallocyclophanes derived from tetradentate Schiff bases
(2004) Lallan Mishra; Kumari Bindu; Subarto Bhattacharya
Tetradentate Schiff bases N,N′-bis(salicylidene)-p- phenylenediamine (LH2) and N,N′-bis(salicylidene)- benzidine, (L′H2) are exploited for the syntheses of Cu(II) and Zn(II) based macrocyclic skeletons and it is found that four phenol molecules bind with a representative Zn(II) complex of LH2. © 2004 Elsevier B.V. All rights reserved.
Synthesis spectroscopic studies, molecular structure optimization, and superoxide dismutase activity of copper(II) and zinc(II) bipyridyl assisted supramolecular motifs containing octadentate schiff base
(2004) Lallan Mishra; Kumari Bindu; Subrato Bhattacharya
Schiff base N,N′,N″,N‴-tetrasalicylidene-3,3′ -diamino-benzidine (H4tsdb) and its dinuclear [M 2(bpy)2.tsdb].2DMSO. 8H2O; bpy=2,2′ -bipyridine; M=Cu(II) 1, M=Zn (II) 2, complexes have been prepared and characterized by their elemental analysis, FAB-mass, IR, NMR ( 1H,13C and 1H-1H COSY), UV-vis, ESR (Cu(II) only) spectra and magnetic-moment data. Force field calculations reveal highly distorted octahedral environment around both the metal centers. The Cu-Cu and Zn-Zn distances are found to be 12.28 and 12.37Å, respectively. Superoxide dismutase activity of the complexes has also been studied.
The X-ray structure of bis(salicylidene)-4,4′-biphenylenediamine
(2002) Lallan Mishra; Kumari Bindu; Lawrence C. Nathan
The X-ray structure of the. Schiff base compound bis(salicylidene)-4,4′-biphenylenediamine (I) has been determined. Crystallographic results are: C26H20N2O2, triclinic, Z P1 = 2, a = 6.141(2) Å, b = 7.213(1)Å, c = 22.219(5)Å, α = 84.60(2)°, β = 88.81(2)°, γ = 89.98(2)°. There are two independent molecules in the unit cell, neither of which is planar. The molecules pack with a somewhat unusual pattern with the aromatic rings of adjacent molecules oriented about half-way between the expected face-to-face or edge-to-face arrangements.