Articles written in Journal of Chemical Sciences
Volume 114 Issue 1 February 2002 pp 1-10 Inorganic and Analytical
Equilibria of the axial ligation of benzyl(aquo)cobaloximes by imidazole, 1-methyl imidazole, histidine, histamine, glycine, ethyl glycine ester, thiourea and urea have been spectrophotometrically measured in aqueous solutions of ionic strength 1.0M (KCl) at 25°C as a function of pH. The equilibrium constants are in the order CN−> 1-methyl imidazole > imidazole > histidine > histamine>glycine>ethyl glycine ester > thiourea > urea. The order of stability of benzyl(ligand)cobaloxime is explained based on the basicity of the ligand, Co(III) →>
Volume 114 Issue 1 February 2002 pp 11-23 Inorganic and Analytical
Equilibria and kinetics of the reaction of bromomethyl(aquo) cobaloxime with histamine, histidine, glycine and ethyl glycine ester and iodomethyl(aquo) cobaloxime with cyanide, imidazole and substituted imidazoles were studied as a function of
Volume 115 Issue 2 April 2003 pp 83-90
Kinetics and equilibria of axial ligation of bromomethyl(aquo) cobaloxime by a series of straight chain primary amines (methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine), cycloamines (cyclopentylamine, cyclohexylamine, cycloheptylamine) and secondary amines (N,N-dimethylamine, N,N-diethylamine) have been measured as functions of pH by spectrophotometric technique in aqueous solution, ionic strength 1 M (KCl) at 25°C. The rate of substitution of H2O varies with the pKa of incoming ligand, thus establishing nucleophilic participation of the ligand in the transition state. Binding and kinetic data are interpreted based on the basicity and steric influence of the entering ligand. To compare the rate constants of the entering ligands, pH independent second-order rate constants (
Volume 115 Issue 3 June 2003 pp 175-183
Equilibria and kinetics of the reactions of chloromethyl(aquo)cobaloxime with histamine, histidine, glycine and ethyl glycine ester were studied as a function of pH at 25°C, 10 M ionic strength (KCl) by spectrophotometric techniques. Comparison of equilibrium constants and rate constants tells that the order is
Volume 116 Issue 3 May 2004 pp 143-150
Equilibrium constants are determined for the reaction of ethylester and methyl ester (aquo) cobaloximes with histamine, histidine, glycine and ethyl glycine ester as a function of pH at 25°C, using spectrophotometric technique. The functional dependence of p
Volume 117 Issue 4 July 2005 pp 305-309
Substitution reactions of propyl cobaloxime with imidazole, substituted imidazoles, histidine, histamine, glycine and ethyl glycine ester are carried out as a function of pH. Trends in the formation constants are explained based on the steric hindrance, extent of π-bonding and Σ-donor capacity of the incoming ligand. Molecular mechanics is used to theoretically determine the bond length and bond strain values by MM2 parametrization and these are correlated with the experimental data.
Volume 119 Issue 1 January 2007 pp 29-34
Spectroscopic characterization (IR, NMR and electronic spectra) of methyl (ligand) cobaloxime was done, where ligand = pyrazole, dimethyl pyrazole, alanine and alanine methyl ester. The frequency changes in the IR spectra and shifts in the NMR were explained on the basis of basicity of the ligand, steric hindrance, HSAB principle and $d\pi-p\pi$ back-bonding from metal to ligand. Alanine and alanine methyl ester form more stable complexes than pyrazole and dimethyl pyrazole. Based on their IR and 1H NMR spectra it is inferred that pyrazole and dimethylpyrazole bind to Co (III) via N-2 ring nitrogen, i.e. monodentate coordination.
Volume 121 Issue 6 November 2009 pp 1053-1060
The kinetics and equilibria for the axial ligation of pyridine and substituted pyridines to bromomethyl(aqua)cobaloxime have been measured spectrophotometrically in aqueous solutions of ionic strength 1.0 M (KC1) at 25°C as a function of 𝑝H. The binding constants and rate of formation increase in the order 4-NH2Py 4-EtPy > 4-MePy > Py > 2-NH2Py > 2-EtPy. The data have been interpreted based on the basicity of the ligand, 𝜋-back bonding from Co(III) → L and hard and soft interactions. The rate of substitution of H2O varies with the pKa of the incoming ligand, thus establishing the existence of nucleophilic participation of the ligand in the transition state. We have investigated the DNA binding of bromomethyl(aqua)cobaloxime with DNA. Bromomethyl(ligand)cobaloximes were isolated and characterized by elemental analysis, IR and NMR (1H, 13C) spectra.
Volume 131 | Issue 9
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