Chemosensor Based on Hydrazinyl Pyridine for Selective Detection of F̄ Ion in Organic Media and CO32− Ions in Aqueous Media: Design, Synthesis, Characterization and Practical Application

Abstract Two new organic receptors, receptors R1 and R2 based on hydrazinyl pyridine have been synthesized for colorimetric detection of fluoride, acetate, and carbonate anions. Receptor R1 selectively recognizes fluoride ions over the other interference anions in the dimethyl sulfoxide based on hydrogen bonding interaction, followed by deprotonation and reflects 1:2 complex formation between the receptor and the fluoride ion. Noticeable, R2 is able to discriminate between fluoride and acetate ions via optical changes despite similar basicity with bathochromic shift of 215 nm and 194 nm. In addition, R1 and R2 exhibit splendid selectivity toward carbonate ions in the aqueous media via visible colour change from pale yellow to aqua with detection limit of 0.51 ppm and 0.47 ppm. The binding mode of fluoride and carbonate to receptor R1 and R2 is supported by Density functional theory calculation. Moreover, receptor R1 and R2 show practical visible colorimetric test strip for the detection of fluoride, acetate, and carbonate ions.