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

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.

Automated summary

The ASC probe was designed for dual sensing of S2O32- ions and GSH based on an ICT process, showing good sensitivity in aqueous DMF medium. It also demonstrated the ability to selectively detect S2O32- ions over other sulfur-containing anions. Additionally, the rationality of the fluorescence off-on responses of ASC to S2O32- and GSH was revealed using DFT and TD-DFT computations.