reaking the Semi-Quinoid Structure: Spin-Switching from Strongly Coupled Singlet to Polarized Triplet State
reaking the Semi-Quinoid Structure: Spin-Switching from Strongly Coupled Singlet to Polarized Triplet State
复制标题
重新解读半醌结构：从强耦合单线态到极化三线态的自旋转换
DOI：
10.1002/chem.201403338
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
and M. Baumgarten
中科院分区：
文献类型：
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作者：
2.P. Ravat;Y. Teki;Y. Ito;E. Gorelik;and M. Baumgarten
研究发现，2，7-TMPNO(4，5，9，10‐tetramethoxypyrene‐2，7‐bis(tert‐butylnitroxide))以半喹类化合物的形式存在，其分子内强磁交换作用达到2J/kB=1185 K，作用距离为10 ä。通过改变温度，观察到活化能为ΔEq=949 K的结构转变，从低温下较多的奎宁结构转变为较高温度下较多的双自由基结构。此外，TREPR谱显示，在光激发下，该分子经历了从单重态到极化三重态的瞬时自旋转变。用混合本征场/精确对角化方法进行光谱模拟，得到自旋哈密顿参数为Bes=1，g=2.0065，D=−0.0112 cm−1，Ande=−0.0014 cm−1。
2,7‐TMPNO (4,5,9,10‐tetramethoxypyrene‐2,7‐bis(tert‐butylnitroxide)) was found to exist in semi‐quinoid form with unprecedented strong intramolecular magnetic exchange interaction of 2J/kB=1185 K operating over a distance of 10 Å. Structural transformations with the activation energy of ΔEeq=949 K were observed by varying the temperature, from more quinoid structure at low temperature to more biradicaloid structure at higher temperature. Moreover, this molecule undergoes a transient spin transition from singlet to polarized triplet state upon photoexcitation revealed by TREPR spectroscopy. The spin Hamiltonian parameters were determined to beS=1,g=2.0065,D=−0.0112 cm−1, andE=−0.0014 cm−1by spectral simulation with the hybrid Eigenfield/exact diagonalization method.