Cu2+-selective naked-eye 'off-on' fluorescent probe with multisignals: chromaticity, fluorescence, electrochemistry

In this study, a rhodamine-acetylferrocene conjugate of RBFc was synthesized and then characterized using spectroscopy and single-crystal analysis. The chemosensor RBFc exhibited a marked colour change from colourless to pink after binding to Cu2+ ions. Importantly, under the presence of the other competing cations in aqueous solution, only Cu2+ ions caused spirolactam ring opening in rhodamine B in RBFc, resulting in an enhanced absorbance of ultraviolet light spectra and fluorescence spectra, as well as obvious shifts in cyclic voltammetry curves and differential pulsed voltammetry curves. The novel probe described in this manuscript provides an attractive approach for detecting Cu2+ in the presence of other multisignals.