Two Mechanism Pathways from a Versatile Arene Ruthenium Assembly: Reaching Aqueous Sensing Reversibility and Selectivity for CN−

The development of highly selective, sensitive and recyclable chemosensors for CN− is critical due to the widespread use of cyanide derivatives in industrial processes and its extreme toxicity to environmental and biological systems. Herein, we report the synthesis and characterization of a water-soluble arene ruthenium metalla-assembly specifically designed to operate in aqueous solutions and under environmentally relevant conditions. The arene ruthenium assembly incorporates functionalized building blocks that enable a selective multi-site recognition of cyanide according to pH by either nucleophilic addition or hydrogen bond interactions. The system exhibits a distinct colorimetric response upon cyanide binding, resulting in a rapid “turn-on” color change. An excellent selectivity and reversibility for cyanide recognition is observed over multiple cycles, with a detection limit in the low micromolar range, thus laying the ground for the future development of sensing technology with supramolecular metal-based assemblies.