Chiral alkynyl Au(I) complexes: Enhancing chiroptical amplification of circularly polarized luminescence through supramolecular helices

The construction of helical structures through self-assembly and the exploration of their formation mechanisms not only amplify chiroptical properties but also provide profound insights into the structures and functions of natural helices. In this study, we developed a chiral Au(I) system based on BINAP and alkynyl ligands. The modification of the length or number of alkyl chains at the terminal positions of the alkynyl ligands significantly impacted the self-assembly behavior of the complexes. Complexes (S)/(R)-2, (S)/(R)-3, (S)/(R)-5, and (S)/(R)-6 demonstrated aggregation-induced circularly polarized luminescence (AICPL). Notably, complexes (S)-6 and (R)-6 were capable of self-assembling into highly ordered helical aggregates, resulting in amplified glum values reaching an order of magnitude of 10-2. The unique double-helix stacking observed in the crystal structure of (R)6 provided a plausible explanation for the formation of such helical aggregates. This research offers a strategy for achieving amplified CPL through artificial helices, providing new insights and guidance for the development of Au(I) complexes with CPL activity.