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.