Supramolecular chiroptical sensing by achiral AIE-active thiols†

Abstract

Rapid and sensitive chiroptical sensing is of great significance for practical applications. Here, a novel rapid supramolecular chiroptical sensing strategy was developed to eliminate possible background interferences and enhance the chiroptical signal by a non-chiral AIE-active thiol click reaction with chiral substrates. These AIE-thiols irreversibly bind amino acids, polypeptides, amines and amino alcohols based on a click-like reaction, and their sensing products further self-assemble, resulting in a higher chiroptical signal output. In particular, the AIE thiol generated from octyloxy-functionalized α-cyanostilbene can form supramolecular helix π–π stacking in the aggregated state, which can greatly contribute to the chiroptical sensing of the target substrate. The self-assemblies obtained from different AIE thiol sensing reactions exhibit different CD and CPL behaviors due to their different self-assembly modes, which are caused by the subtle differences in the non-covalent C–H⋯π, [π⋯π] and hydrogen bonding interactions of the chiroptical sensing reaction product. Their high reactivity and robust self-assembly sensing mechanism eliminate the interference of chiral substrates and their impurities, improving sensor sensitivity and selectivity. This strategy provides a simple and promising means of detecting chiral molecules, especially those without UV optical activity.