Enhancing probe's sensitivity for peroxynitrite through alkoxy modification of dicyanovinylchromene.

An intramolecular charge transfer (ICT)-based fluorescent probe P-ONOO- was synthesized to detect ONOO-. After responding to peroxynitrite, the dicyano-vinyl group of P-ONOO- generates the aldehyde group, emitting strong green fluorescence accompanied by quenching of the yellow fluorescence. According to the calculated Fukui function, the modification of the alkoxy group can enhance the f+ of P-ONOO-, which can enhance the probe's nucleophilic addition reactivity with ONOO-. It has been experimentally verified that P-ONOO- shows fast response (within 30 s), excellent sensitivity (the detection limit = 10.4 nM), and good selectivity towards ONOO-. Additionally, the probe P-ONOO- has high membrane permeability and good biocompatibility, which can image endogenous ONOO- and exogenous ONOO- in HeLa cells.