Investigation on transition States of [Alanine + M~(2+)] (M = Ca, Cu, and Zn) complexes: A quantum chemical study

摘要

The ground state geometries of [Alanine (Ala) + M~(2+)] [M = Ca, Cu, and Zn) complexes were calculated in gas phase at B3LYP/6-311++G(d,p) level of theory. Transition states (TSs) between different stable conformers of [Ala + M~(2+)] complexes were also calculated. Among the different [Ala + M~(2+)] complexes, the complex where metal cations coordinated to carboxylate group (?COO?) is found to be energetically most favorable. To calculate TSs, the ground state structures of any two conformers of [Ala + M~(2+)] complexes were used. The ground state energies of two stable conformers and their TS structures were used to calculate the activation energy. The reactivity of different conformers of [Ala + M~(2+)] complexes have been discussed in terms of energy difference between their highest occupied molecular orbital and lowest unoccupied molecular orbital.