A Highly Selective “Turn-on” Fluorescent Probe for Detection of Fe 3+ in Cells

A new “turn-on” fluorescent probe Py based on rhodamine and piperonaldehyde was designed and synthesized for detecting Fe 3+ in cells. The free probe Py was non-fluorescent. While only upon addition of Fe 3+ , the significant increase of the fluorescence and color were observed which could be visible directly by “naked-eye”. The probe Py shows high selectivity and sensitivity for Fe 3+ over other common metal ions in EtOH-H 2 O (3/2, v /v) mixed solution. The association constant and the detection limit were calculated to be 4.81 × 10 4 M −1 and 1.18 × 10 −8 mol/L respectively. The introduction of piperonaldehyde unit could increase probe rigidity which could enhance its optical properties. Meanwhile, the binding mode between Py and Fe 3+ was found to be a 1:1 complex formation. The density functional theory (DFT) calculations were performed which would further confirm the recognition mechanism between probe Py and Fe 3+ . In addition, the probe has been proved to be reversible for detecting Fe 3+ . Moreover, the probe Py was used to detect Fe 3+ in cells successfully.