Novel triphenylamine-connected indolinium fluorescence sensor for detection of the cyanide anion and DFT calculations

Abstract

A new triphenylamine based probe (TPA) for detection of the cyanide anion (CN−) was designed and synthesized. In aqueous solution, TPA showed rapid fluorescence response and excellent selectivity for CN− ions, and other anions did not affect the detection process. The probe displays a detection limit of 1.17 µM which is lower than the threshold (1.9 µM) regulated by the World Health Organization (WHO) for CN− ions in aqueous solution. The sensitivity and photophysical properties of TPA were investigated using UV–Vis spectrophotometry, fluorescence spectrofluorometry, and 1H NMR titration techniques. Density functional theory (DFT) calculations were carried out to better understand the relationship between the photophysical properties and the electronic structures of TPA and TPA-CN.