Li Guo-Ling, Kanegawa Shinji, Yao Zi-Shuo, Su Sheng-Qun, Wu Shu-Qi, Huang You-Gui, Kang Soonchul, Sato Osamu
Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku, 819-0395, Fukuoka, Japan.
Chemistry. 2016 Nov 21;22(48):17130-17135. doi: 10.1002/chem.201603817. Epub 2016 Oct 11.
Two polymorphic structures have been well determined in a valence tautomeric (VT) dinuclear cobalt complex. These polymorphs showed distinct thermal- and photomagnetic behavior, and are thus ideal for studying the "pure" intermolecular factors to VT transitions. In polymorph 1A, the VT cations are arranged head-to-waist with their neighbors and exhibit weak π⋅⋅⋅π interactions, resulting in a gradual and incomplete thermal VT transition. In contrast, the cations in polymorph 1B are arranged head-to-tail and exhibit relatively strong π⋅⋅⋅π interactions, leading to an abrupt and complete thermal VT transition with adjustable hysteresis loop at around room temperature. The VT process for both polymorphs can be induced by light, but the light-excited state of 1B⋅2H O has a higher thermal relaxation temperature than that of 1A⋅3H O.
在一个价互变异构（VT）双核钴配合物中，两种多晶型结构已得到很好的确定。这些多晶型物表现出不同的热磁和光磁行为，因此是研究VT转变中“纯粹”分子间因素的理想对象。在多晶型物1A中，VT阳离子与其相邻阳离子以头对腰的方式排列，并表现出较弱的π⋅⋅⋅π相互作用，导致热VT转变逐渐且不完全。相比之下，多晶型物1B中的阳离子以头对尾的方式排列，并表现出相对较强的π⋅⋅⋅π相互作用，导致在室温附近出现突然且完全的热VT转变，并伴有可调节的滞后回线。两种多晶型物的VT过程都可以由光诱导，但1B⋅2H₂O的光激发态比1A⋅3H₂O具有更高的热弛豫温度。
