The title compound 2,2-dithiophene-naphthopyran (C21H14OS2, Mr = 346.44) was synthesized and characterized by IR, 1H NMR, elemental analysis and single-crystal X-ray diffrac- tion. It belongs to the monoclinic system, space group P21/n, with a = 8.2349(14), b = 6.1964(11), c = 32.458(5) , β = 95.051(3)°, V = 1649.8(5) 3, Z = 4, Dc = 1.395 g/cm3, μ = 0.327 cm-1, F(000) = 720, the final R = 0.0559 and wR = 0.1442 for 3370 observed reflections (I > 2σ(I)). X-ray analysis revealed that the interatomic distance of C(13)-O(1) is 1.456(3) , longer than that of normal C-O bond (1.41～1.43) in a six-membered heterocycle. The UV-vis spectra of the title compound showed that it exhibits excellent photochromic property in polyester coating and solutions.
The title compound, 2,2-bis(4-tertial butyl phenyl) naphthopyran, has been prepared and characterized by means of IR, 1H NMR and elemental analysis, and its crystal structure was determined with X-ray diffraction in the ring-opened form after hydrolyzation. It belongs to monoclinic, space group P21/c, with a = 14.358(3), b = 7.6725(15), c = 24.470(5) , β = 97.147(4)°, C33H36O2, Mr = 464.62, V = 2674.8(9)3, Z = 4, Dc = 1.154 g/cm3, μ = 0.070 mm-1, F(000) = 1000, the final R = 0.0514 and wR = 0.1272 for 5444 observed reflections (I > 2σ(I)). X-ray analysis revealed that the C(13)-O(1) bond of the title compound cracks after UV irradiation, the six-membered heterocycles are destroyed, and zwitterionic intermediates come into being. The molecular structure in the ring-opened form is obtained after hydrolyzation. It is infrequent that the single-crystal structure is determined in a ring-opened form. A two-dimensional framework is formed by O-H···O and CAr-H···O hydrogen bonds. The UV-vis spectra show that the title compound exhibits excellent photochromic properties in solutions and polymers.
