A novel coumarin-based fluorogenic probe bearing the tris unit (DAT-1) with high selectivity and suitable affinity toward Fe3+ over other cations tested was developed in biological systems. The sensing mechanism was studied by quantum calculations. The probe can be applied to the monitoring of Fe3+ in aqueous solution with a pH span of 3–8. In addition, biological imaging, membrane permeability and nontoxicity demonstrate that DAT-1 could act as a turn-off fluorescent chemosensor for Fe3+ in living cells.
