Rationale Strategy to Tune the Optical Properties of Gold Catenane Nanoclusters by Doping with Silver Atoms
Srestha Basu, Martina Perić Bakulić, Hussein Fakhouri, Isabelle Russier‐Antoine, Christophe Moulin, Pierre‐François Brevet, Vlasta Bonačić‐Koutecký, Rodolphe Antoine
Abstract
We report the chemical substitution-mediated doping of silver atoms into Au10SG10 (SG: glutathione) catenane nanoclusters (NCs) in a controllable manner. Two levels of doping were conducted leading to two silver-doped Au10–xAgxSG10 nanoclusters (with x = 0–2 and x = 1–4). Optical studies reveal that nanoclusters with a high level of doping (x = 1–4) show a blue shift in absorption and a significant red shift of ∼50 nm in the two-photon-excited emission spectrum with respect to pristine Au10SG10. The preservation of the catenane structure is confirmed by comparing the experimental and computational X-ray diffraction patterns and absorption spectra of Au10SG10 and its silver-doped analogs. In order to better address the structure–property relationship in such catenane clusters, further theoretical investigations were performed at the DFT level. A high-energy shift of the S1 state is evidenced in the calculated one-photon absorption spectra due to a larger s to d gap in silver caused by smaller relativistic effects in comparison to the gold atoms. Furthermore, the red shift in the two-photon excited emission band of the clusters is due to significantly larger calculated relaxation of the first excited state in nanoclusters with a high level of silver doping.