Specific recognition of Cu2+ by simple spiropyran via forming a ternary complex of spiropyran-Cu2+-DMF

A novel ternary complex of Spiropyran-Cu2+-DMF is formed from photochromic spiropyran derivatives with simple sturcutre. The complex was characterized by methods of 1H NMR and ESIeMS and the binding stoichiometry of the spiropyran, Cu2+, and DMF in the complex is 1:1:1. With this complex, Cu2+ can be specifically recognized to naked eye amongst other common metal ions (Ba2+, Cd2+, Co2+, Cr3+, Fe3+, Fe2+, Mn2+, Ni2+, Zn2+, Mg2+, K+, Na+, Li+, Ca2+, Sn2+, Pb2+, Al3+). The spiropyran was structurally simple enough and avoided to chemically append other ligating groups onto spiropyran brackets via complicated chemical synthesis process that was generally indispensable for other spiropyran-depentdent ions recoginition in the literature.