摘要

The reaction mechanism of cationic Au(I) N-heterocyclic carbine (NHC) complexes [(R(2)Im)(2)Au](+) (R = Me, Et, i-Pr, and n-Pr) binding to Cys and Sec residues for the monofunctional and bifunctional substitution reaction was studied using the density functional theory with the B3LYP functional. The optimized geometries reveal the transition state configuration of Au(I) complex exhibited trigonal planar configuration. Over-investigation of the activation energies of all the complexes demonstrated that Me group complexes were more favorable in monofunctional substitution reaction, while the bifunctional substitution reaction preferred i-Pr group complexes. In addition, the reaction of Au(I) complexes binding to the active site Sec selenol was stronger than to the active site Cys thiols. Moreover, to consider the environment effect, we employed the isoelectric focusing polarizable continuum model to calculate the single-point energy in dependence of the dielectric constant epsilon, observing the environment was a weeny impact on the binding of Au(I) NHC complexes to its intracellular targets.