Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Photoswitching of magnetic interaction: diarylethene photochromic spin couplers
Autore:
Matsuda, K; Irie, M;
Indirizzi:
Kyushu Univ, Dept Chem & Biochem, Grad Sch Engn, Higashi Ku, Fukuoka 8128581, Japan Kyushu Univ Fukuoka Japan 8128581 gn, Higashi Ku, Fukuoka 8128581, Japan Japan Sci & Technol Corp, CREST, Higashi Ku, Fukuoka 8128581, Japan Japan Sci & Technol Corp Fukuoka Japan 8128581 u, Fukuoka 8128581, Japan
Titolo Testata:
POLYHEDRON
fascicolo: 11-14, volume: 20, anno: 2001,
pagine: 1391 - 1395
SICI:
0277-5387(20010530)20:11-14<1391:POMIDP>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
REVERSIBLE PHOTOCYCLIZATION; DERIVATIVES; SYSTEMS; FILMS;
Keywords:
ESR spectroscopy; diarylethene; photochromic reaction; intramolecular magnetic interaction;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
23
Recensione:
Indirizzi per estratti:
Indirizzo: Matsuda, K Kyushu Univ, Dept Chem & Biochem, Grad Sch Engn, Higashi Ku, 6-10-1 Hakozaki, Fukuoka 8128581, Japan Kyushu Univ 6-10-1 Hakozaki Fukuoka Japan 8128581 28581, Japan
Citazione:
K. Matsuda e M. Irie, "Photoswitching of magnetic interaction: diarylethene photochromic spin couplers", POLYHEDRON, 20(11-14), 2001, pp. 1391-1395

Abstract

We have synthesized 1,2-bis[6-(1-oxyl-3-oxide-4,4,5,5-tetramethylimidazolin-2-yl)-2-methylbenzo [b]thiophen-3-yl]hexafluorocyclopentene (2a) which shows photoswitching of intramolecular magnetic interaction between two nitronyl nitroxide radicals. Compound 2 showed ideal photochromic performance. The conversions from open-ring form isomer 2a to closed-ring form isomer 2b,and from 2b to 2a were both almost 100%. From the magnetic measurement it was found that while the two spins of the open-ring form isomer 2a weakly interact with each other (2J/k(B) = - 2.2 K) due to the disconnection of thepi -systems, spins of 2b have remarkable antiferromagnetic interaction (2J/k(B) = - 11.6 K). The EPR spectra were measured for both 2a and 2b in benzene solution at room temperature. In both cases, the ESR spectra showed nine lines indicating that the exchange interaction between the two radicals was much stronger than the hyperfine coupling constant. We have also synthesized 3a, in which two nitronyl nitroxides were located at both ends of 1,2-bis(6-phenyl-2-methyl-1-benzothiophen-3-yl)hexafluorocyclopentene. Two p-phenylene groups are introduced to regulate the strength of the exchange interaction between spins at nitronyl nitroxide and to detect the change of theinteraction by ESR spectroscopy. Compound 3 underwent reversible photochromic reactions in ethyl acetate by irradiation with 313 and 578 nm light. The photochromic reaction proceeded both ways almost completely. While the ESR spectrum of 3a showed complex 15 lines, the spectrum of 3b showed nine lines. The double integrals of the spectra at the initial and photostationarystates were almost identical, indicating that there is no gain or loss of the amount of the spins during the photochromic reaction. (C) 2001 ElsevierScience Ltd. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 02/10/20 alle ore 01:41:39