Pyridinium-fused pyridinone: A novel "turn-on" fluorescent chemodosimeter for cyanide

Abstract

A new chemodosimeter based on pyridinium-fused pyridinone iodide (PI) has been obtained through a "clean reaction" method. This compound can detect CN- in aqueous solution with a high selectivity and rapid response. The detection of CN- occurs through the nucleophilic attack of CN- on the C=N bond, which induces the destruction of the π-conjugation on the pyridinium ring. Support of this detection mechanism was obtained by 1H NMR titration, HR-MS, and DFT calculations. Upon the addition of 10 equivalents CN- to a solution of PI in THF/H 2O (1:1, v/v), a 57-fold enhancement in fluorescence intensity was observed at the maximum emission wavelength of 457 nm. Meanwhile, the maximum absorption wavelength was also blue-shifted from 447 nm to 355 nm. Other common anions such as BF4-, PF6-, F -, Cl-, Br-, I-, H 2PO4-, ClO4-, CH 3COO-, NO2-, N3-, and SCN- had little effect on the detection of CN -. The response time of PI for CN- was less than 5 seconds. The detection limit was calculated to be 5.4×10-8 M, which is lower than the maximum permission concentration in drinking water (1.9 μM) set by the World Health Organization (WHO). Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.