Chemoselective and enantioselective fluorescent recognition of lysine by a BINOL-pyridine-based chiral dialdehyde

A BINOL-pyridine-based chiral unsymmetric dialdehyde was synthesized. This compound in combination with Zn 2+ has exhibited highly chemoselective as well as enantioselective fluorescent response toward lysine, an essential amino acid. It was found that this compound undergoes regioselective macrocyclization with l -lysine but generates a more complex mixture with d -lysine. This difference in reactivity should contribute to the observed chemo- and enantioselectivty in the fluorescence response. This molecular probe can be used at 20 times lower concentration than a previously reported analog for lysine recognition. It has also displayed significantly enhanced enantioselectivity over the previously reported analog with the enantioselective fluorescence intensity ratio (ef) increased from 16.9 to 60.0 [ef = (I L -I 0 )/(I D -I 0 ). I 0 : the fluorescence intensity of the probe in the absence of the amino acid].