A BODIPY derivative as a highly selective “Off–On” fluorescent chemosensor for hydrogen sulfate anion

Abstract

A new fluorescent receptor 1 for anions has been synthesized by the combination of BODIPY dye and indole moiety. The binding and sensing abilities of receptor 1 toward various anions have been studied by absorption, emission and ¹H NMR titrations spectroscopies. Receptor 1 could act as a highly selective “Off–On” fluorescent sensor for hydrogen sulfate anion in CH₃CN solvent and CH₃CN–H₂O medium. The fluorescence response of receptor 1 toward HSO₄⁻ in CH₃CN solvent could be due to the suppressed PET (photo-induced electron transfer) process induced by the multiple hydrogen bonding interactions between receptor 1 and HSO₄⁻. In CH₃CN–H₂O medium, the HSO₄⁻-induced change is mainly the consequence of a simple protonation of the CHN– moiety of receptor 1, which inhibited the PET process and "turned on" the fluorescence of 1.