Enantioselective fluorescent recognition of chiral acids by 3- and 3,3′-aminomethyl substituted BINOLs

Benzylaminomethyl groups are introduced to the 3,3′-positions of BINOL. The resulting compounds can be used to conduct the enantioselective fluorescent recognition of mandelic acid and N-benzyloxycarbonylphenylglycine. In the presence of (S)-mandelic acid, compound showed over 30-fold fluorescence enhancement with the ef [ef=enantiomeric fluorescence difference ratio=(IS−I0)/(IR−I0)] up to 4.2. In the presence of d-N-benzyloxycarbonylphenylglycine, compound showed up to 15-fold fluorescence enhancement with the ef up to 5.0. These high fluorescence sensitivity and enantioselectivity make compounds and practically useful sensors for the recognition of the chiral acids in apolar solvents.