Controllable and reversible sensing cyanide ion using dual-functional Cu(II)-based ensemble

In this work, a dual-functional Cu 2+ -based ensemble (2 S ·Cu 2+ ) was well designed and characterized. Then, the successional and discriminating sensing for CN − over other competitive species (H 2 PO 4 − and biothiols) was achieved based on the disaggregation of 2 S ·Cu 2+ ensemble and the deprotonation of imidazole NH of regenerated sensor S in aqueous solution, respectively. The visual sensing mechanism could be clearly demonstrated by 1 H NMR, HRMS and energy changes between the HOMO−LUMO band gaps. Furthermore, the reversibility and reusability of S and 2 S ·Cu 2+ upon alternating addition of CN − /H + and CN − /Cu 2+ were studied. Interestingly, the sequential sensing for biothiols (cysteine, glutathione and homocysteine) and CN − was also realized through spectroscopic methodology and test paper strips. This work may provide a feasible strategy to discriminate CN − over H 2 PO 4 − and biothiols with high selectivity and sensitivity through Cu 2+ -based ensembles.