A novel turn-on fluorogenic aldehyde-appended salamo-like copper(ii) complex probe for the simultaneous detection of S2O32− and GSH

Abstract

A novel turn-on fluorogenic aldehyde-appended salamo-like copper(II) complex probe (ASC) was rationally designed and exploited for the two-pronged sensing of thiosulfate (S₂O₃²⁻) ions and glutathione (GSH) based on an intramolecular charge transfer (ICT) process, which could be fully characterized by using various spectroscopic techniques. It is worth noting that the solid-state crystal structure of the Cu(II) complex is rarely different from its structure in solution (ASC) through a single-crystal X-ray diffraction experiment. Importantly, the developed probe exhibited good sensitivity in response to S₂O₃²⁻ and GSH in an aqueous DMF medium within a detection limit of 149 and 131 nM, respectively. Meanwhile, the designed complex probe could be capable of discriminatively detecting S₂O₃²⁻ ions over other sulfur-containing anions. The probe ASC was applied in real water samples utilizing tap water and rain water for the detection of the S₂O₃²⁻ ion. In addition, this probe could be successfully applied to test strips towards S₂O₃²⁻ and GSH. Finally, we unveiled the rationality of the fluorescence “off–on” responses of ASC to S₂O₃²⁻ and GSH by means of density functional theory (DFT) and time-dependent density functional theory (TD-DFT) computations.