Atomically precise chiral silver clusters based on non-chiral ligands for acid/base stimulated luminescence response

Abstract

Chiral metal nanoclusters synthesized by non-chiral ligands are usually in the form of racemates. Thus, resolving racemic compounds continues to be a great challenge. Herein, we report a case of the racemic compound hexanuclear silver cluster (Ag₆-Rac) protected by the non-chiral sulfhydryl ligand sodium 1H-1,2,3-triazole-5-thiolate (SHTT) and 2,6-bis(diphenylphosphino)pyridine (dpppy). The homochiral clusters in Ag₆-Rac are able to spontaneously crystallize and undergo chiral resolution to obtain a racemic conglomerate (Ag₆-S/Ag₆-R) by solvent-induced crystallization. Interestingly, the Ag₆-Rac clusters exhibit strong luminescence in solid and solution, which can respond to trifluoroacetic acid (TFA) and reversible cycling over five times using diethylamine (DEA). This work provides a new research model for resolving racemic clusters and constructing stimulus-responsive clusters.