Solvent controlled sugar–rhodamine fluorescence sensor for Cu2+ detection

A "turn-on" fluorescence probe for Cu(2+) detection has been reported according to a Cu(2+) triggered spirolactam ring-opening reaction. The probe is a double-responsive fluorescent and colorimetric Cu(2+)-specific sensor in aqueous solution containing 20% of acetonitrile with high selectivity and excellent sensitivity (limit of detection is 12 μg L(-1)). Furthermore, the significant color changes visible to the naked eye at the concentration of 3 μM (ca. 0.20 mg L(-1)) are about ten times lower than the WHO (World Health Organization) recommended level (2.0 mg L(-1)) for Cu(2+) ions in drinking water.