Easily accessible ferric ion chemosensor based on rhodamine derivative and its reversible OFF-ON fluorescence response

An easily accessible ferric ion (Fe3+) fluorescence chemosensor was designed and synthesized via microwave reaction based on rhodamine derivative. This sensor displayed a favorable selectivity for Fe3+ ion over a range of other common metal cations in acetonitrile/Tris buffer (4:1, v/v, pH 7.0) with a 1:1 stoichiometry, leading to prominent fluorescence OFF-ON switching of the rhodamine fluorophore. The association constant between the sensor and Fe3+ was determined to be 1.51×105, and the corresponding detection limit was calculated to be 3.2×10−7 M according to fluorescence titration analysis. The recognizing behavior of the chemosensor toward Fe3+ has been investigated in detail by FTIR, NMR, and HRMS measurements. Additionally, the recognition process of the chemosensor for Fe3+ is chemically reversible on the addition of phosphate anion (PO43−).