摘要/Abstract
以双齿配位的草酸根为配体和FeCl3反应得到了化合物{(Me2NH2)2[Fe2(ox)2Cl4]•H2O} n (ox=oxalate) ( 1•H2O). 在真空和加热的条件下, 1•H2O脱水发生单晶到单晶的转变, 得到了化合物{(Me2NH2)2[Fe2(ox)2Cl4]} n ( 1). 磁性研究表明客体水分子存在与否对化合物磁相互作用没有明显影响. 介电性质研究表明客体水分子的存在可影响化合物中客体胺和氢原子的动态弛豫过程. 化合物 1•H2O在250 K, 80 K和50 K呈现三个介电弛豫过程, 而化合物 1仅在80 K表现出单一弛豫过程.
关键词: 介电弛豫, 单晶-单晶转化, 水, 磁性
It is well known that water is one of the most important chemical constituent in the nature, and thus is regarded as the genesis of life. Meanwhile, water plays an irreplaceable role in biology process, such as regulating the affinity between fatty acids and alkyl chains and controlling the conformation of DNA. In the crystal chemistry, water molecules in compounds will also significantly affect its structure, physical and chemical properties. Among them, single crystal to single crystal (SCSC) transformations induced by water molecules have attracted great attention, because those transformations often change the physical properties such as magnetic, dielectric and proton conduction. More importantly, it is facile to obtain detailed structural information, which leads to more directly and better understanding the transformation mechanism and structure-properties relationship. In this work, we report the SCSC transformation in the compound of {(Me2NH2)2- [Fe2(ox)2Cl4]•H2O} n (ox=oxalate) ( 1•H2O), which was prepared through the hydrothermal reaction of oxalate and FeCl3 in the presence of dimethylamine chloride. Under vacuum and heating conditions, 1•H2O underwent SCSC transformations, formed compound 1. 1•H2O and 1 were characterized by X-ray single-crystal diffraction, powder X-ray diffraction, magnetic, dielectric and thermogravimetric analysis. Magnetic studies on 1•H2O and 1 show that the presence or absence of guest water molecules had no significant effect on their magnetic interaction. Investigation on the dielectric properties of 1•H2O and 1 reveals that the presence of guest water molecules can influence the dynamic relaxation process of guest amine and water in the compound. Compound 1•H2O exhibited three dielectric relaxations at 250 K, 80 K and 50 K respectively, while 1 only showed a single relaxation process at 80 K. This work sheds light on the further exploration of SCSC transformations associated with the dielectric relaxation.
Key words: dielectric relaxation, SCSC structural transformation, water, magnetism
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