Cu2+-selective “Off–On” chemsensor based on the rhodamine derivative bearing 8-hydroxyquinoline moiety and its application in live cell imaging

A rhodamine-based fluorescence chemsensor bearing the 8-hydroxyquinoline unit is developed as a reversible turn-on chemosensor for Cu2+. It exhibits a highly sensitive fluorescent response toward Cu2+ in aqueous media with an 80-fold fluorescence intensity enhancement under 10 equiv. of Cu2+ added. This indicates that the synthesized chemosensor effectively avoided the fluorescence quenching for the paramagnetic nature of Cu2+ via its strong binding capability toward Cu2+. The chemosensor Rh-Q exhibits a dynamic response range for Cu2+ from 2 × 10−7 to 5 × 10−5 M, with a detection limit of 0.19 μM, and good selectivity for Cu2+ over other heavy and transition metal (HTM) ions in Tris–HCl/EtOH (7:3, v/v, pH 7.4). In addition, the turn-on fluorescent change upon the addition of Cu2+ is also applied in cell imaging.