An 2-(2 '-aminophenyl)benzoxazole-based OFF-ON fluorescent chemosensor for Zn2+ in aqueous solution

A water-soluble fluorescent sensor, 1, based on the receptor-spacer-fluorophore [2-(2'-aminophenyl)benzoxazole-amide-2-picolylamine] sensor platform, demonstrates the high sensitivity for Zn2+ with a 25-fold fluorescence enhancement upon chelation to Zn2+ and also exhibits high selectivity to Zn2+ over other metal ions. X-ray crystal structure of Zn2+ complex reveals that the amide oxygen (O2) cooperates with 2-picolylamine unit (N3, N4) as a receptor bind Zn2+.