A highly selective and sensitive fluorescent chemosensor for detection of CN−, SO32− and Fe3+ based on aggregation-induced emission

Abstract

A novel fluorescence chemosensor 1 with aggregation-induced emission was designed and synthesized through a nucleophilic addition reaction between cyanide and triphenylamine. It exhibited remarkable selectivity and high sensitivity and was able to detect Fe³⁺, CN⁻ and SO₃²⁻ in almost pure aqueous solution with low detection limits of 1.44 μM, 9.88 nM and 0.107 μM, respectively. Job's plot and ¹H NMR data showed that the binding stoichiometry of 1 with Fe³⁺, CN⁻ or SO₃²⁻ was 1 : 1. Further observations of ¹H NMR titration suggested that a coordination bond was formed between two cyano of 1 and Fe³⁺ which resulted in fluorescence quenching of 1 after detection of Fe³⁺, whereas the nucleophilic addition of cyanide or sulfite to the vinyl group was responsible for the fluorescent quenching of CN⁻ or SO₃²⁻ toward 1. The biological applications of 1 were also evaluated and it was found to exhibit low cytotoxicity and membrane permeability. In addition, 1 could also be made into test strips to detect Fe³⁺ and CN⁻ and was employed as a sensor for detection Fe³⁺ in living cells.