A single colorimetric sensor for multiple target ions: the simultaneous detection of Fe2+ and Cu2+ in aqueous media

This study demonstrates the design, synthesis and sensing properties of a simple and efficient chemosensor 1 (1 = 2,6-bis((2-(((pyridine-2-yl)methylamino)methyl)phenol)ethylamido)pyridine) to rapidly detect Fe2+ and Cu2+ in aqueous solution (bis-tris buffer/DMF (8/2, v/v)), exploiting UV-vis spectral analysis, naked-eye and paper devices. The sensor 1 showed significant absorption spectra at 455 nm for Fe2+ and 660 nm for Cu2+, which are responsible for color changes due to the metal-to-ligand charge-transfer. The binding modes of 1 with Fe2+ or Cu2+ have been investigated by Job plot and ESI-mass analysis. In addition, the sensor 1 could be recyclable simply through treatment with a proper reagent such as EDTA. Moreover, the sensor has been used in the development of practically viable colorimetric kits.