A hydrophilic naphthalimide-based fluorescence chemosensor for Cu2+ ion: Sensing properties, cell imaging and molecular logic behavior

In this work, a hydrophilic naphthalimide-based fluorescence chemosensor (sensor 1) was synthesized for Cu2+ recognition, in which 2-(2-aminoethoxy)ethanol was introduced to improve the hydrophily and Schiff base acted as the multidentate ligand for Cu2+. The effect factors, sensing mechanism and regenerability of sensor 1 for Cu2+ sensing were systematically investigated. It was found that sensor 1 displayed a long emission wavelength of 532 nm upon excited in visible light region (436 nm). and the good water solubility made it utilized in aqueous media. It could selectively react with Cu2+ over other common metal ions to form a 2:1 complex within 1 min and result in significant fluorescence quench. The fluorescence change was linear to 0.5-10.0 mu mol L-1 of Cu2+ with a low detection limit of 3.74 x 10(-8) mol L-1. Sensor 1 has been successfully utilized for analyzing Cu2+ in water samples as well as imaging cellular Cu2+. Moreover, in view of fluorescence on-off-on switches of sensor 1 induced by Cu2+ and EDTA, an IMPLICATION logic gate was constructed based on fluorescence mode with Cu2+ and EDTA as inputs. (C) 2020 Elsevier B.V. All rights reserved.