Synthesis, Structure and Photochromism of a New Diarylethene and Its Ag(I) Complex

A new symmetric diarylethene containing cyano group was synthesized and structurally characterized by elemental analysis, IR, H-1 NMR and X-ray single-crystal diffraction. It belongs to the monoclinic system, space group C2/c with a = 18.848(6), b = 8.561(2), c = 16.875(5) angstrom, beta = 100.398(6)degrees, V = 1344.6(11) angstrom(3), Z = 4, mu = 0.262 mm(-1), D-c = 1.415 g/cm(3), M-r = 570.56, F(000) = 1160, the final R = 0.0808 and wR = 0.2107 with I > 2 sigma(I). The two thienyls adopt reactive anti-parallel conformation and the carbon distance of photocyclization is 3.57 angstrom. The neighboring molecules are stacked closely with C-(HF)-F-center dot center dot center dot hydrogen bonding. In addition, the photochromism of the new compound was investigated in solvents with different polarity and PMMA film. The alternative photo-irradiation of 254 nm light and >= 550 visible light can induce the reversible photo-cyclization and photo-reversion with the color interconversion between colorlessness and blue. In THF solution, the lambda(max) of diarylethene in PSS in visible band is 585 nm. The diarylethene further reacted with AgBF4 in benzene to give rise to complex 1, which was structurally characterized by elemental analysis, IR, ESI-MS and TG. 1 demonstrated reversible photochromism in both solution and PMMA film. The complexation of metal ions with diarylethene leads to a minor red-shift of the lambda(max) of 1 in THF in PSS to 590 nm.