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高等学校化学研究 ›› 1999, Vol. 15 ›› Issue (2): 174-181.

• Articles • 上一篇    下一篇

An EPR Study on Intramolecular Spin Exchange, Rotational Mobility of Nitroxides Linked by a Long-chain

Yoshimi Sueishi, Katsumi Noritake, LIU Ying-jin   

  1. Department of Chemistry, Faculty of Science, Okayama University, Tsushima Naka 3-1-1, Okayama 700-8530, Japan
  • 收稿日期:1998-11-19 出版日期:1999-04-24 发布日期:2011-08-17
  • 通讯作者: Yoshimi Sueishi

An EPR Study on Intramolecular Spin Exchange, Rotational Mobility of Nitroxides Linked by a Long-chain

Yoshimi Sueishi, Katsumi Noritake, LIU Ying-jin   

  1. Department of Chemistry, Faculty of Science, Okayama University, Tsushima Naka 3-1-1, Okayama 700-8530, Japan
  • Received:1998-11-19 Online:1999-04-24 Published:2011-08-17

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摘要： The effects of pressure, solvent on the intramolecular spin exchange of biradicals having two nitroxide fragments linked by a long flexible chain were studied by means of highpressure EPR technique. It was found that the intramolecular exchange interaction between nitroxides of biradical took place through the direct contact between them. By analyzing the observed EPR spectra, we have estimated the ratio(Τin/Τout) value of the average lifetime of the radical fragments inside a cage(Τin) to that outside the cage(Τout). The Τin/Τout values decreased with decreasing temperature, increasing pressure. The results suggest that the nearly cyclic conformation in a cage is favorable in solution. Fur ther, the rotational correlation time of individual nitroxide was estimated from the anisotropic EPR signal,, the information on the segmental motion of the nitroxide group in biradical was obtained.

关键词: EPR, Spin exchange, Pressure effect, Rotational correlation time

Abstract: The effects of pressure, solvent on the intramolecular spin exchange of biradicals having two nitroxide fragments linked by a long flexible chain were studied by means of highpressure EPR technique. It was found that the intramolecular exchange interaction between nitroxides of biradical took place through the direct contact between them. By analyzing the observed EPR spectra, we have estimated the ratio(Τin/Τout) value of the average lifetime of the radical fragments inside a cage(Τin) to that outside the cage(Τout). The Τin/Τout values decreased with decreasing temperature, increasing pressure. The results suggest that the nearly cyclic conformation in a cage is favorable in solution. Fur ther, the rotational correlation time of individual nitroxide was estimated from the anisotropic EPR signal,, the information on the segmental motion of the nitroxide group in biradical was obtained.

Key words: EPR, Spin exchange, Pressure effect, Rotational correlation time