Rapid colorimetric sensing of cyanide anion in aqueous media with a spiropyran derivative containing a dinitrophenolate moiety

A spiropyran derivative containing a dinitrophenolate moiety (2: 1',3',3'-trimethy1-6,8-dinitro-spiro-[2H-1-benzopyran-2,2'-indoline]) behaves as a receptor for selective detection of cyanide anion (CN-) in aqueous media. Compound 2, when dissolved in aqueous media, spontaneously produces the spirocycle-opened merocyanine (MC) form even in dark condition. The absorption band of the MC form decreases selectively upon addition of CN-, via a nucleophilic addition of CN- to the spirocarbon of the MC form. The nucleophilic addition occurs very rapidly (within 1 mill) and enables rapid and selective quantification of very low levels of CN- (>0.8 mu M) by an absorption analysis. (C) 2011 Elsevier Ltd. All rights reserved.