An Enantiopair of Organic Ferromagnet Crystals Based on Helical Molecular Packing of Achiral Organic Radicals
An Enantiopair of Organic Ferromagnet Crystals Based on Helical Molecular Packing of Achiral Organic Radicals
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DOI：
10.1021/jz2014105
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发表时间：
2011-11
影响因子：
5.7
通讯作者：
D. Shiomi;Y. Kanzaki;Shou Okada;Ryosuke Arima;Y. Miyazaki;A. Inaba;R. Tanaka;Kazunobu Sato;T. Takui
中科院分区：
文献类型：
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作者：
D. Shiomi;Y. Kanzaki;Shou Okada;Ryosuke Arima;Y. Miyazaki;A. Inaba;R. Tanaka;Kazunobu Sato;T. Takui
本文报道了具有结构手性的有机分子晶体中的铁磁有序现象。已发现非手性自由基1以两种对映体结晶，手性空间群为P43和P41。P43形式（1 L）具有左手堆叠的分子，在结晶固体中具有螺旋手性。在P41（1 R）的另一种形式中，右手堆叠对应于1 L的镜像。磁化率测量表明，两种晶体在TC = 1.1K时均发生铁磁相变。铁磁有序已被证实的热容测量。磁热容量在TC = 1.1 K处呈现出一个λ形峰，熵变为R ln 2，与S = 1/2自旋的预期一致。这是第一个真正的有机分子为基础的铁磁性与结构手性的基础上螺旋分子包装在结晶固体的例子。
We report the ferromagnetic ordering phenomena occurring in organic molecular crystals with structural chirality. Achiral radical 1 has been found to crystallize in two enantiomorphs with chiral space groups of P43 and P41. The P43 form (1L) has left-handed stacking of the molecules, giving the helical chirality in a crystalline solid. In the other form of P41 (1R), the right-handed stacking corresponds to a mirror image of 1L. Magnetic susceptibility measurements show that both the crystals undergo a ferromagnetic phase transition at TC = 1.1 K. The ferromagnetic ordering has been confirmed by heat capacity measurements. The magnetic heat capacity exhibits a λ-shaped peak at TC = 1.1 K with an entropy change of R ln 2, as expected for S = 1/2 spins. This is the first example of genuinely organic molecule-based ferromagnetism associated with the structural chirality based on the helical molecular packing in the crystalline solid.