Off-on switchable chemosensor based on rhodamine armed with morpholine moiety

We have synthesized a novel morpholine functionalized rhodamine derivative RBM which specifically binds to Fe3+ in the presence of large excess of other competing metal ions. The chemosensor is highly selective for Fe3+ over other cations. Meanwhile, the distinct color changes and rapid switch-on fluorescence also provide “naked eyes” detection for Fe3+ over a broad pH range. The chemosensor also displays 1:1 complex formation with Fe3+ ion, with a detection limit of 2.1 µM in aqueous CH3CN solution, showing that it may offer potential as a chemosensor for the detection of submillimolar Fe3+ ions in physiological environments.