An efficient ruthenium tris(bipyridine)-based luminescent chemosensor for recognition of Cu(II) and sulfide anion in water

A novel efficient luminescent chemosensor based on a 1,4,7,10-tetraazacyclododecane (cyclen)-tethered Ru(bpy)32+ derivative (Ru–cyclen) has been synthesized and characterized. It displays an ON–OFF-type luminescence change with excellent selectivity towards Cu(II) amongst 16 metal ions in 100% aqueous solution. The binding stoichiometry of Ru–cyclen with Cu2+ was established by Job plot analysis and mass spectral evidence. Furthermore, the in situ generated Ru–cyclen–Cu ensemble recovered luminescence in the presence of S2−, indicating an ‘OFF–ON’-type sensing process. Similar phenomena were not observed with other common anions and biothiols, making it a high selective sulfide probe. Finally, the sensing mechanism is confirmed to be displacement approach by NMR, mass and emission spectrometry.