A reversible Em-FRET rhodamine-based chemosensor for carboxylate anions using a ditopic receptor strategy

Abstract

A reversible rhodamine-based sensor (L1) capable of undergoing excimer-fluorescent resonance energy transfer (Em-FRET) was designed and synthesized using a ditopic receptor strategy. Addition of Cu2+ ions to a solution of L1 induced a ring-open conformation of spirolactam (Em-FRET ON), whilst ring closure was induced upon addition of CH3COO− (Em-FRET OFF).