Chromogenic Signaling Probes with Different "N, O" Donors for Fe³⁺ Sensing and Cell Imaging

Iron, as the most prevalent critical trace element in the human body, is crucial for many basic physiological functions and has many environmental applications. Therefore, excellent chemosensors with high sensitivity and good selectivity toward iron are highly desired. Three new fluorescent colorimetric chemosensors (CS1, CS2, and CS3) were synthesized and prepared through a one-step reaction to selectively detect Fe³⁺ in aqueous media. To effectively coordinate metal ions, the sensors contain rhodamine derivatives with different "N, O" donor atoms. Of these sensors, CS2 and CS3 demonstrated sensing behavior and colorimetric "off–on" sensing for Fe³⁺ over various biologically important metal ions, rendering good selectivity. Fluorescent imaging was performed to confirm the possibility of applying the sensors in living cells.