Turn-off fluorescence sensing of benzenediols via guest-induced π-conjugation switching in bisimidazole-based hydrindacene allosteric receptors

Abstract

Fluorescent bisimidazole-based hydrindacene allosteric receptors 1a–c and 2 were synthesized for nonlinear ON/OFF sensing of benzenediols. By tuning their D–π–D conjugation through substituent modification, these receptors were designed to function as turn-off fluorescent sensors based on the cleavage of their π-conjugation accompanied by binding with benzenediols. The cooperative allosteric binding demonstrated selective and efficient nonlinear quenching toward orcinol.