Regulation of chromenylium fluorophore with a built-in recognition site for the detection of sulfite

Abstract

A double charged cationic pyridinium-fused chromenylium analogue DMCQ with an acceptor-π-acceptor (A-π-A) electronic structure was designed and prepared for the sensitive and selective detection of SO32-. Undergoing a Michael addition reaction with SO32- at the built-in pyridinium moiety in the chromenylium fluorophore, the π-electron structure of the chromenylium skeleton transferred from (A-π-A) to (A-π-D) system along with a prominent fluorescence enhancement. Based on this specific addition reaction, the probe DMCQ exhibits high selectivity for the detection of SO32- over other biological related species within a wide pH range (4-11). As the highly electron-deficient nature of the pyridinium-fused chromenylium accelerated the reaction with SO32-, the probe turned out a rapid response time (60 sec), together with a high sensitivity (33 nM). Besides, DMCQ could not only image SO32- in living cells but also monitor SO32- in food and water samples with a satisfactory recovery (81.30-112.89 %).