Synthesis and Crystal Structure of 1-(2-Methyl-5-formyl-3-thienyl)-2-(2-methoxylphenyl)perfluorocyclopentene

A new family of photochromic diarylethene compounds, 1-(2-methyl-5-formyl-3- thienyl)-2-(2-methoxylphenyl)perfluorocyclopentene (1o) having an unsymmetrically substituted hexafluorocyclopentene unit, was synthesized and its structure was determined. The crystal belongs to the monoclinic system, space group P21/c with a = 15.4866(5), b = 9.0744(9), c = 12.6906(3), β = 90.1480(10)°, Z = 4, V = 1783.4(3)3, Dc = 1.513 mg/m3, μ = 0.25, F(000) = 824, the final R = 0.0579 and wR = 0.1566 for 2584 observed reflections (I > 2σ(I)). Interestingly, a colorless compound 1o undergoes photocyclization upon irradiation of UV light to give the blue isomer diarylethene. Upon irradiation with visible light with wavelength greater than 510 nm, the blue compound can return to its initial colorless state.