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Titolo:
Photochromism of 1,2-bis(2-ethyl-5-phenyl-3-thienyl)perfluorocyclopentene in a single-crystalline phase. Conrotatory thermal cycloreversion of the closed-ring isomer
Autore:
Kobatake, S; Shibata, K; Uchida, K; Irie, M;
Indirizzi:
Kyushu Univ, Grad Sch Engn, Dept Chem & Biochem, Higashi Ku, Fukuoka 8128581, Japan Kyushu Univ Fukuoka Japan 8128581 em, Higashi Ku, Fukuoka 8128581, Japan CREST, Japan Sci & Technol Corp, Higashi Ku, Fukuoka 8128581, Japan CRESTFukuoka Japan 8128581 nol Corp, Higashi Ku, Fukuoka 8128581, Japan Ryukoku Univ, Dept Chem Mat, Otsu, Shiga 5202194, Japan Ryukoku Univ OtsuShiga Japan 5202194 hem Mat, Otsu, Shiga 5202194, Japan
Titolo Testata:
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
fascicolo: 49, volume: 122, anno: 2000,
pagine: 12135 - 12141
SICI:
0002-7863(200012)122:49<12135:PO1I>2.0.ZU;2-E
Fonte:
ISI
Lingua:
ENG
Soggetto:
REVERSIBLE PHOTOCYCLIZATION; DIARYLETHENE DERIVATIVES; SYSTEMS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Physical, Chemical & Earth Sciences
Citazioni:
24
Recensione:
Indirizzi per estratti:
Indirizzo: Irie, M Kyushu Univ, Grad Sch Engn, Dept Chem & Biochem, Higashi Ku, Fukuoka 8128581, Japan Kyushu Univ Fukuoka Japan 8128581 shi Ku, Fukuoka 8128581, Japan
Citazione:
S. Kobatake et al., "Photochromism of 1,2-bis(2-ethyl-5-phenyl-3-thienyl)perfluorocyclopentene in a single-crystalline phase. Conrotatory thermal cycloreversion of the closed-ring isomer", J AM CHEM S, 122(49), 2000, pp. 12135-12141

Abstract

1,2-Bis(2-ethyl-5-phenyl-3-thienyl)perfluorocyclopentene (1a) was found toundergo a thermally reversible photochromic reaction in solution as well as in the single-crystalline phase. Upon irradiation with ultraviolet light the hexane or toluene solution containing la and single-crystal la turned blue along with the formation of closed-ring isomer (Ib). The blue solution and single crystal returned colorless by irradiation with visible light (lambda > 500 nm) or heating above 100 degreesC. The bleaching is due to the cycloreversion of Ib to la. The thermal cycloreversion activation energies were measured in the toluene solution and in the single-crystalline phase above 100 degreesC. The activation energy from photogenerated Ib to la in thesolution was 128 kJ mol(-1), while it decreased to 120 kJ mol(-1) in the crystal of the open-ring isomer la. In the crystal of the closed-ring isomerIb the energy increased to 137 kJ mol(-1). The cycloreversion reaction wasfound to be controlled by the environmental conditions. The thermal cycloreversion reaction in the crystal was directly followed by X-ray crystallography and revealed to proceed in a conrotatory mode, which is opposed to thegeneral Woodward-Hoffmann rules.

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Documento generato il 26/09/20 alle ore 05:01:47