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合成并用X-射线单晶衍射表征了一个离子对化合物1,7-bis(1-methylimidazolium)heptane bis(maleonitriodithiolato)nickelate(1)的结构。沿着晶体学c轴方向,化合物1中的阴、阳离子分别排列形成波浪形的链。变温介电性质研究表明,化合物1在90℃左右展现了介电态转变。我们将此转变归于化合物1中平衡阳离子的有序到无序转变。在低频区,化合物1出现了明显的介电弛豫过程,这与阳离子偶极运动有关。此外,DSC研究表明,在第二个升温过程中,化合物1在66℃和130℃左右出现两步冷结晶。此种冷结晶现象在小分子化合物中很罕见,这与化合物1的较大粘度以及测试过程中的较快降温速率有关。
The structure of an ion pair compound 1,7-bis (1-methylimidazolium) heptane bis (maleonitriodithiolato) nickelate (1) was synthesized and characterized by X-ray single crystal diffraction. Along the crystallographic c-axis direction, the anions and cations in compound 1 are arranged to form wavy chains, respectively. Studies on the properties of variable temperature dielectric show that compound 1 exhibits dielectric state transition at about 90 ℃. We attribute this transition to the order-to-disorder transition of the equilibrium cations in compound 1. In the low frequency region, Compound 1 shows obvious dielectric relaxation process, which is related to the cation dipole motion. In addition, DSC studies showed that during the second temperature increase, Compound 1 showed two steps of cold crystallization at about 66 ° C and about 130 ° C. This cold crystallization phenomenon is rare in small molecule compounds, which is related to the greater viscosity of Compound 1 and the faster rate of cooling during the test.