Development of rhodamine-based fluorescent probes for sensitive detection of Fe3+ in water: spectroscopic and computational investigations

Four novel rhodamine-based fluorescent probes (RE1–RE4) were designed and synthesized for sensitive detection of Fe3+ in water. RE1–RE4 exhibited low detection limits in the range of 18.6 nM to 29.4 nM. In addition, the binding modes of the probes (RE1–RE4) with Fe3+ were proved to be 1 : 1 stoichiometry of the complexes by Job's plot and also their complexing ability was determined using the binding constants (RE2 > RE4 > RE3 > RE1). RE2 was selected to study the proposed binding mechanism with Fe3+ by ESI-MS, 1H NMR and DFT calculations. Furthermore, RE2 was further utilized to detect Fe3+ in living cells and real water samples, indicating its promising prospect in biological and environmental fields.