Strategically Modified Rhodamine–Quinoline Conjugate as a CHEF-Assisted FRET Probe for Au³⁺: DFT and Living Cell Imaging Studies

Abstract

A systematic journey from O-donor through S-donor to N-donor chelator led to the development of a highly selective Au(3+) chemosensor that operates via a CHEF-induced FRET mechanism. This sensing protocol avoids unwanted possible side reactions observed in alkyne-based gold sensors. DFT studies strongly support the experimental facts. The probe RT-2 detects Au(3+) in the presence of the masking agent KI to minimize Hg(2+) interference; however, RQ-2 selectively detects Au(3+) without any interference and shows reversibility in the sensing in the presence of tetrabutylammonium cyanide. The probe efficiently images Au(3+) in living HeLa cells under a fluorescence microscope.