A highly selective and sensitive sugar–rhodamine “turn-on” fluorescent sensor for divalent copper ion detection in acetonitrile

A “turn-on” sugar–rhodamine fluorescent probe for Cu2+ detection in CH3CN has been designed and synthesized according to a Cu2+ triggered spirolactam ring-opening reaction. The introduction of sugar into probe molecule, combining with solvent effect, significantly improved its selectivity and sensitivity. The synthesized probe exhibits high Cu2+ selectivity and excellent sensitivity (limit of detection is ca. 10 μg/L) in acetonitrile media. The limit of detection is about 200 times lower than the World Health Organization (WHO) recommended level (2.0 mg/L) for Cu2+ ions in drinking water.