Enantioselective fluorescent sensing of chiral carboxylic acid by engaging boronic acid and BINOL

摘要

Two BINOL based boronate esters, namely (S)-2 and (S)-3, were designed and synthesized. Fluorescent recognition studies of (S)-2 towards enantiomers of mandelic acid revealed that sensor (S)-2 exhibited high fluorescent enantioselective response towards mandelic acid. The other boronate ester (S)-3 which did not have hydroxyl group in the minor groove of BINOL did not show any fluorescent chiral discrimina tion. Their enantioselective recognition was also studied by means of~1 H NMR spectroscopy. The results indicated that the sensor (S)-2 was very promising as a chiral fluorescent sensor for the recognition of chiral carboxylic acid in THF solvent. Theoretically predicted hydrogen bonding interactions revealed a favorable chiral recognition between the receptor and L-mandelic acid, which is well correlated with experimentally observed enantioselective recognition phenomenon.