The Structure and Photochromism of 2,4,4,6-Tetraphenyl-4H-thiopyran

Autor:	Mojmír Adamec, Jaroslav Vojtěchovský, J. Hašek, Stanislav Nešpůrek
Rok vydání:	1992
Předmět:	Thiopyran chemistry.chemical_compound Photochromism Crystallography chemistry Absorption band X-ray crystallography Cyclohexane conformation Orthorhombic crystal system General Chemistry Crystal structure Ring (chemistry)
Zdroj:	Collection of Czechoslovak Chemical Communications. 57:1326-1334
ISSN:	1212-6950 0010-0765
DOI:	10.1135/cccc19921326
Popis:	2,4,4,6-Tetraphenyl-4H-thiopyran, C29H22S, orthorhombic, Pna21, a = 17.980(4), b = 6.956(2), c = 34.562(11) Å, V = 4323(2) Å3, Z = 8, Dx = 1.237 g cm-3, F(000) = 1696, λ(CuKα) = 1.54184 A, μ = 1.372 mm-2, T = 294 K. The final R was 0.050 for the unique set of 3103 observed reflections. The central 4H-thiopyran ring forms a boat conformation for both symmetrically independent molecules with average boat angles 4.4(3) and 6.8(3)° at S and C(sp3), respectively. The mean planes of phenyls at the position 2 and 6 are turned from the double plane of 4H-thiopyran by 42.5(5) and 35.8(3)°, respectively. The investigated material undergoes a photochromic change in the solid state after irradiation with UV light or X-rays. The maximum of the new absorption band is situated at 564 nm. The non-exponential time dependence of photochromic bleaching is analysed in terms of a dispersive first-order reaction.
Databáze:	OpenAIRE
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