Enantioselective Recognition of Lysine and Phenylalanine Using an Imidazole Salt-Type Fluorescent Probe Based on H8-BINOL

An imidazole bromide fluorescent probe (R)-1 based on chiral H-8-BINOL was synthesized with a high yield; it was found to have good enantioselective recognition of lysine and phenylalanine using fluorescence analysis. When L-lysine was recognized, the enantioselective fluorescence enhancement ratio was 2.7 (ef = I-L - I-0/I-D - I-0, ef = 2.7, 20 eq Lys); as the amount of L-Lys increased, a distinct red shift was observed (the wavelength varied by 55.6 nm, 0-100 eq L-Lys), whereas D-Lys had a minimal red shift. The generation of this red shift phenomenon was probably due to the ICT effect; the probe's intramolecular charge transfer was affected after (R)-1 bound to L-Lys, and this charge transfer was enhanced, leading to a red shift in fluorescence. In addition to the enantioselective recognition of lysine, phenylalanine was also recognized; the enantioselective fluorescence enhancement ratio was 5.1 (ef = I-L - I-0/I-D - I-0, ef = 5.1, 20 eq Phe).

Automated summary

An imidazole bromide fluorescent probe (R)-1 based on chiral H-8-BINOL was synthesized, which showed good enantioselective recognition of lysine and phenylalanine using fluorescence analysis. The study explained the mechanisms of fluorescence enhancement and red shift, and demonstrated the ability of the probe to selectively recognize chiral amino acids.