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Titolo:
Photochromic properties of cationic merocyanine dyes. Thermal stability ofthe spiropyran form produced by irradiation with visible light
Autore:
Yagi, S; Maeda, K; Nakazumi, H;
Indirizzi:
Univ Osaka Prefecture, Coll Engn, Dept Appl Mat Sci, Osaka 5998531, Japan Univ Osaka Prefecture Osaka Japan 5998531 Mat Sci, Osaka 5998531, Japan
Titolo Testata:
JOURNAL OF MATERIALS CHEMISTRY
fascicolo: 12, volume: 9, anno: 1999,
pagine: 2991 - 2997
SICI:
0959-9428(1999)9:12<2991:PPOCMD>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
LANGMUIR-BLODGETT-FILMS; POLY(METHYL METHACRYLATE); PHOTOCHEMICAL PROPERTIES; SIDE-GROUPS; POLYMERS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Engineering, Computing & Technology
Citazioni:
23
Recensione:
Indirizzi per estratti:
Indirizzo: Nakazumi, H Univ Osaka Prefecture, Coll Engn, Dept Appl Mat Sci, 1-1 Gakuen Cho, Osaka5998531, Japan Univ Osaka Prefecture 1-1 Gakuen Cho Osaka Japan 5998531 apan
Citazione:
S. Yagi et al., "Photochromic properties of cationic merocyanine dyes. Thermal stability ofthe spiropyran form produced by irradiation with visible light", J MAT CHEM, 9(12), 1999, pp. 2991-2997

Abstract

A series of novel cationic merocyanine dyes were prepared by condensation of 1,2,3,3-tetramethylindolium derivatives and 3-formyl-4H-1-benzothiopyranor -benzopyran derivatives, and their photochromic properties were investigated, especially focusing on the substituent effect in the indolium moiety. These dyes were converted into the spiropyran (SP) form so as to be colorless by irradiation with visible light, although, left under darkness, the colored merocyanine (MC) form was reproduced. The thermal coloration was affected by two factors: the substituent in the indolium moiety and the counter anion. An electron-donating substituent such as a methoxy group at the 5position effectively retarded the thermal coloration, whereas an electron-withdrawing group such as a nitro group accelerated it. These substituent effects afforded good linearity for the Hammett rule with para sigma parameters, indicating that decrease of the electron density in the indoline moiety of the SP form facilitated heterolytic cleavage of the bond between the spiro carbon and the oxygen of the pyran ring.

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Documento generato il 23/09/20 alle ore 20:05:11