Isophorone-boronate ester: A simple chemosensor for optical detection of fluoride anion

Abstract

A highly selective isophorone-boronate ester based chemosensor, (1), having a dicyanovinyl moiety as a convenient colorimetric probe, has been designed. Different types of anionic analyte such as CH3COO−, ClO4−, Cl−, F−, PF6−, Br− and HSO4− were tested and among them only highly nucleophilic F− anion displayed significant response towards the sensor. Addition of the fluoride anion across the boron atom disrupts the π-conjugation thereby shifts the absorption wavelength towards the redshift region due to the decrease in the HOMO-LUMO energy gap and a colour change from yellow to blue is observed under visible light condition. The detection limit of this probe was calculated to be 3.25 × 10—8 M for fluoride anion. The binding constants and the detection limits of the sensor were calculated using absorption titration studies. The silica gel TLC strips dip-coated by the chemosensor (1) revealed a colour change from yellow to brick red to naked eye.