4-Functionalized terpyridine derivative as dual responsive chemosensor for biologically important inorganic cations and fluoride anion

Abstract

A dual responsive sensor molecule, 2-(4-(2,2′:6′,2″-terpyridin)-4′-yl-phenyl)-N-methyl-3-thiosemicarbazone, has been synthesized and characterized using standard analytical and spectroscopic techniques. The dual binding properties of the sensor molecule were investigated using biologically important inorganic cations (Mn2+, Fe2+, Ni2+, Cu2+, Zn2+, Pb2+ and Hg2+) and anions (F¯, Cl¯, Br¯, I¯, HSO4¯ and H2PO4¯). The sensor molecule is equipped with analyte coordinating donor sites displaying charge transfer controlled spectroscopic properties and shows analyte–receptor interactions. Sensing mechanism involving host–guest interactions was confirmed by spectral and cyclic voltammetry techniques. The receptor shows colorimetric signalling in solution for cations such as Mn2+, Ni2+ and Cu2+ as evidenced by instant colour changes even at 2 μL aliquots of manganese and copper cations, and 4 μL aliquot for nickel cation, among the studied cations. Fluoride anion was detected by naked eye even at 2 μL of aliquot, signalled by the development of yellowish brown colour, through hydrogen bonding, deprotonation of N–H fragment and formation of HF2¯. Thus, the receptor shows dual sensing ability towards selected cations and F¯ anion. Further, paper strip experiments on receptor were also employed for the detection of cations and fluoride anion in solution.