DFT studies on ureido-peptide functionalized Au4M2 bimetallic nanoclusters

Abstract

Binding of bimetallic gold nanoclusters with ureido-peptide and its charge transfer properties were studied using density functional theory (DFT). All the geometries of UP-[Au4M2] hybrids were optimized with CAM-B3LYP hybrid functional, where two types bonding modes were observed depending upon the nature of Ureido peptide (UP) and Bimetallic gold nanocluster (BGNC). The carboxylate end of ureido-peptide (monodentate and bidentate mode), oxygen at ureido end (monodentate) interacts with the metal cluster through O-M conventional bond while non-conventional bond is obvious through the ureido end. UP found to interact with metal cluster in neutral and UP- in cationic form. The binding of UP alters the chemical stability of hybrid. However, the polarization at the UP unit remains unaltered. The redox and optical properties of UP bound BGNCs was performed to calculate charge transfer in the presence of external stimuli. Born-Oppenheimer approximation based Frozen nuclei approach has been employed to compute the time scale of hole migration dynamics after sudden local ionization. The hole was evolving with time and the migration is found completely based on binding modes and localization of eigen functions.