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

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 Cu 2+ 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 Cu 2+ indicated DASA-1 binds to Cu 2+ with a ratio of 1:1, and the 1 H NMR titration spectrum of Cu 2+ on DASAs as well as the UV–Vis absorption spectra with adding Cu 2+ 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 Cu 2+ sensor with high selectivity and sensitivity.