An efficient triazole-based fluorescent “turn-on” receptor for naked-eye recognition of F− and AcO−: UV–visible, fluorescence and 1H NMR studies

An efficient colorimetric receptor was developed by a simple convenient method which exhibited naked-eye sensitivity for fluoride and acetate in a biologically competing solvent like DMSO. The receptor developed, portrayed a substantial change in the UV–visible absorption characteristics upon addition of fluoride and acetate anions over other anions. The binding constants showed that the binding ability of receptor towards F− anion was slightly higher than that of the AcO− anion. Jobʹs plots indicated the formation of a (1:1) complex (receptor:anion) of receptor with fluoride and acetate anions respectively. A “turn on” fluorescence response with a red shift was observed upon fluorescence titration. 1H NMR titration experiments revealed the mechanism to be driven by the hydrogen bonding interaction of amide NH and phenol OH of the receptor molecule which was followed by deprotonation in the receptor by the F− and AcO− anions.