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

[Display omitted] •Two BINOL based boronate esters, namely (S)-2 and (S)-3, were designed and synthesized.•Sensor (S)-2 exhibited high fluorescent enantioselective response towards mandelic acid.•(l)-Mandelic acid exerts a greater quenching effect on the fluorescence intensity of (S)-2 than (d)-mandelic acid.•Similar to mandelic acid (d)- and (l)- lactc acid is also having different fluorescence quenching effect.•In case of Boc protected amino acids the difference in fluorescence quenching is less. 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 discrimination. Their enantioselective recognition was also studied by means of 1H 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.