Molecular Mechanics and Semi-empirical Analysis of the Interaction Between Co~(2+)and the Amino Acids in Solution in Water

摘要

The interaction between Co~(2+)and amino acids,viz.,L-histidine and L-arginine in solution in water has been investigated by UV-visible spectrophotometry using the technique of continuous variation and molecular modeling.For the metal ion and the two amino acid combinations,absorbance values at lambda_(max)were plotted against concentrations of reactants.The maxima in the absorbance vs.concentration graphs gave the ratios at which the metal ion and amino acids combined.Cobalt(II)is found to form predominantly 1:4 complex with L-histidine and 1:3 complex with L-arginine.The proposed structures of the complexes have been optimized and their electronic spectra generated based on molecular mechanics and semi-empirical calculations.Comparison of the observed and predicted electronic spectra suggested the most likely structures present in solution.