Single fluorescein-based probe for selective colorimetric and fluorometric dual sensing of Al3+ and Cu2+

An efficient fluorescein based probe (H2L) for the dual sensing of Al3+ and Cu2+ has been synthesized and characterized. H2L was highly selective toward these two ions with different fluorescence signals and binding modes in two different media. In EtOH-H2O (3:2, v/v; pH 4.0), H2L selectively binds Al3+ to form a 1:1 ligand/metal complex, giving rise to a visible pale pink-to-yellow color change and fluorescence enhancement at 440 nm, while in CH3CN-H2O (2:3, v/v; pH 7.2), H2L and Cu2+ form a 1:2 ratio complex, resulting in a color change from pink to orange-yellow and a significant fluorescence enhancement at 520 nm. The binding modes were confirmed by fluorescence, absorption, IR, ESI-MS and H-1 NMR titrations. The detection limits were calculated to be 7.32 x 10(-8) M and 1.47 x 10(-8) M for Al3+ and Cu2+, respectively. Cell imaging studies demonstrate that this sensor is capable of sensing Al3+ and Cu2+ in living cells. (C) 2017 Elsevier B.V. All rights reserved.