Stimuli-Responsive Photoluminescent Molecular Tweezers for Highly Enantioselective Discrimination of Chiral Primary Amines

To address the challenge of chiral recognition in terms of efficiency and generality, we propose a novel fluorescence sensing approach by rationally designing metal-ion-responsive chiral molecular tweezers. The flexible and adaptable molecular tweezers enable facile recognition of 31 structurally varied chiral primary amine compounds, including amino acids, amino acid esters, and chiral amines. Notably, upon stimulation by zinc ions, the chiral molecular tweezers demonstrate a higher enantioselective fluorescence response. Combined density functional theory calculations reveal that the chiral sensing mechanism relies on differential reaction rates and potential hydrogen-bonding interactions between the two enantiomers and the chiral receptor, which results in one of the enantiomers forming a more abundant, stable, and structurally rigid complex with the receptor, resulting in a significant increase in the fluorescence intensity and enantioselectivity. The stimuli-responsive molecular tweezers approach provides a novel strategy for precise stereocontrol and universality of chiral recognition, offering a promising tool for applications in various fields.