【作者】 李勇； 王琪； 吴国是；

【Author】 Yong LI Qi WANG Guo-Shi WU Department of Chemistry,Tsinghua University,Beijing 100084

【机构】 清华大学化学系；

【摘要】 <正>在对杯芳烃双基自由基Ⅰ(图1)的高温 ESR 研究中,我们发现了可逆的热致磁变效应,即Ⅰ的 ESR 信号随温度的变化发生了可逆而有规律的改变。更多还原

【Abstract】 ESR studies of I were carried out in toluene at high dilution.A typical spectrum of nitroxide biradical was observed at room temperature.Justifying from the ESR lineshape and computer simulation,the spectrum can be regarded as an overlap of a broad triplet and a quintet which shows the fast intramolecular spin exchange.No obvious change was found when the toluene solution of I was heated below 353K. However,over that the ESR signals were enhanced and the triplet lines gradually split into 3×3 peaks,which are assignable to the hyperfine coupling of the two ortho hydrogen nuclei of the phenyl ring.Interestingly,reversible changes of ESR spectra induced by heating were observed.The reversible change could be easily reproduced for many times without destructions of the sample.A rational explanation based on the thermo-induced conformational transitions of I is given.更多还原