Stereospecific solid-state [2+2] autophotocycloaddition of a styryl dye containing a 18-crown-6 fragment |
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Authors: | A I Vedernikov S P Gromov N A Lobova L G Kuz'mina Yu A Strelenko J A K Howard M V Alfimov |
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Institution: | (1) Photochemistry Center, Russian Academy of Sciences, 7a ul. Novatorov, 119421 Moscow, Russian Federation;(2) N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky prosp., 119991 Moscow, Russian Federation;(3) N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation;(4) Department of Chemistry, University of Durham, South Road, Durham, DH1 3LE, UK |
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Abstract: | A procedure was developed for the synthesis of a 18-crown-6-containing styryl dye of the pyridine series. Phototransformation
products of the dye that formed upon irradiation with visible light in solution, films, and crystals were studied by 1H and 13C NMR spectroscopy and spectrophotometry. Irradiation of solutions of this dye in acetonitrile leads only to reversible E-Z photoisomerization of the C=C bond. Irradiation of a film of the dye induces stereospecific 2+2] photocycloaddition to form
exclusively the rctt isomer of tetrasubstituted cyclobutane. The latter was found to undergo base-catalyzed isomerization giving rise to the rcct isomer. X-ray diffraction study showed that photocycloaddition occurs in single crystals without their destruction. The structures
of the E isomer of the dye and the resulting rctt isomer of the cyclobutane derivative were established. The characteristic features of the molecular packing of the dye favorable
for topochemical photocycloaddition in the crystal and the structural changes that accompany the cyclobutane formation are
discussed.
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Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1896–1908, August, 2005. |
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Keywords: | crown ethers styryl dyes structure photoisomerization photocycloaddition topochemical single-crystal-to-single-crystal reaction cyclobutanes |
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