Role of size and shape selectivity in interaction between gold nanoclusters and imidazole: a theoretical study

International audienceWe present a theoretical study on the structure, stability, spectra and electronic properties of imidazole (Im) adsorbed on gold nanoclusters (Aun, n = 2, 4, 6, 8, 10, and 20). These computations are performed using various density functional theories with and without inclusion of Grimme’s (D3) dispersion correction. For small clusters, we also carried out wavefunction based ab initio (MP2 and SCS-MP2) computations for comparison. Vibrational, AIM and NBO analyses clearly reveal the occurrence of charge transfer (CT) through covalent (N1-Au) and noncovalent interactions that play important roles in the stability of the Im@Aun complexes with anchor assisted H-bonds (Cα-H•••Au). Therefore, gold clusters can act as H-bond acceptor with biomolecules for development of new materials and applications. Our study establishes also the ability and reliability of PBE0 and M05-2X functionals compared to B3LYP and PBE for the accurate description of covalent and noncovalent interactions between Im and gold clusters since they lead to close agreement with MP2. Finally, we show that Au8 cluster may be viewed as large enough to mimic 3D gold surface