Imidazoanthraquinone-triarylamines based Chromofluorogenic Chemosensors for Anion Sensing

Abstract

In this report, imidazoanthraquinone-triarylamines fluorescent probe have examined for their coordination behaviour against tetrabutylammonium (TBA) salts of various anions in DMSO solvent. The anionic sensing ability of dyes was monitored by using colorimetric technique, UV−Vis absorption/emission spectroscopy. Among the various anions used, the probes were found selectively sensitive towards F−, CN− and OH− ions and show marked anion-induced colorimetric and optical response with red-shifted intramolecular charge transfer (ICT) absorption and emission band. The red shift in optical signal of all sensors established a deprotonation mechanism involving the −NH moiety of the imidazole ring. Besides, anion selectivity for probe-analyte interaction was found to be depended on the acidity/binding unit of sensor and basicity/hardness of anions (F− >CN− >OH−). Additionally, presence of electron donor or acceptor substituents on triarylamine also alters the chromogenic response or binding affinity of the sensors and found to be decreased with increase in ICT character. Further, low detection limit and high stability constant obtained from titration studies of ~10–6 M sensors than previously reported ~10–5 M imidazoanthraquinone sensors makes them strong selective and sensitive anionic-chemosensors.