Rhodamine-based “turn-on” fluorescent probe with high selectivity for Fe2+ imaging in living cells

A rhodamine-based “turn-on” fluorescent probe 1 was synthesized. 1 displays high selectivity toward Fe2+ without interfering by other transition metal ions. And 1 exhibits a stable response for Fe2+ over a concentration range from 2 μM to 24 μM. Their fluorescent enhancement is observed in the presence of Fe2+ because of the ring-open interactions of spirocyclic. In addition, confocal laser scanning microscopy experiments have proven that probe can be used to monitor Fe2+ in living cells.