A rhodamine-based "turn-on" fluorescent chemodosimeter for Cu2+ and its application in living cell imaging.

A new fluorescent probe 1, N-(Rhodamine-6G)lactam-hydrazinecarbothioamide, was synthesized as a fluorescent and colorimetric chemodosimeter in aqueous solution for Cu(2+). Following Cu(2+)-promoted ring opening, redox and hydrolysis reactions, comparable amplifications of absorption and fluorescence signals were observed upon addition of Cu(2+); this suggests that chemodosimeter 1 effectively avoided the fluorescence quenching caused by the paramagnetic nature of Cu(2+). Importantly, 1 can selectively recognize Cu(2+) in aqueous media in the presence of other trace metal ions in organisms, abundant cellular cations and the prevalent toxic metal ions in the environment with high sensitivity (detection limit <3 ppb) and a rapid response time (<2 min). In addition, the biological imaging study has demonstrated that 1 can detect Cu(2+) in the living cells.