A Chiral Porous Metal-Organic Framework for Highly Sensitive and Enantioselective Fluorescence Sensing of Amino Alcohols

A highly porous and fluorescent metal-organic framework (MOF), 1, was built from a chiral tetracarboxylate bridging ligand derived from 1,1'-bi-2-naphthol (BINOL) and a cadmium carboxylate infinite-chain secondary building unit. The fluorescence of 1 can be effectively quenched by amino alcohols via H-bonding with the binaphthol moieties decorating the MOF, leading to a remarkable chiral sensor for amino alcohols with greatly enhanced sensitivity and enantioselectivity over BINOL-based homogeneous systems. The higher detection sensitivity of 1 is due to a preconcentration effect by which the analytes are absorbed and concentrated inside the MOF channels, whereas the higher enantioselectivity of 1 is believed to result from enhanced chiral discrimination owing to the cavity confinement effect and the conformational rigidity of the BINOL groups in the framework. 1 was quenched by four chiral amino alcohols with unprecedentedly high Stern-Volmer constants of 490-31200 M-1 and enantioselectivity ratios of 1.17-3.12.