Visible light/Cu2+ dual triggered photochromic donor-acceptor stenhouse adducts: Synthesis, properties and applications

Abstract Light is not the only stimuli which can coverts donor-acceptor Stenhouse adducts (DASAs) from the triene to the cyclopentenone form. Here, we firstly demonstrate that Cu2+ can drive linear-to-cyclic isomerization of DASAs in acetonitrile, which increase the rate of color fading. Three different generations of DASAs (DASA-1, DASA-2, and DASA-3) have been synthesized by Knoevenagel condensation to verify the universal applicability of the mechanism by which copper ions discolor DASAs. The Job’s plot of DASA-1 to Cu2+ indicated DASA-1 binds to Cu2+ with a ratio of 1:1, and the 1H-NMR titration spectrum of Cu2+ on DASAs as well as the UV-Vis absorption spectra with adding Cu2+ showed that copper ions could induce the process of linear-to-cyclic isomerization of DASAs in acetonitrile. Based on this, we propose copper ions as the eraser of a DASA derived ink to achieve repeatable erasing. Furthermore, DASAs have been utilized as a Cu2+ sensor with high selectivity and sensitivity.