基于1-乙基-1,4-二氮杂二环[2.2.2]辛烷配体相变材料的合成及性质研究

Novel gyrotropic phase transition material based on 1-ethyl-1,4-diazonia-bicyclo [2.2.2] octane

通过溶液法将1-乙基-1,4-二氮杂二环[2.2.2]辛烷与溴化锌反应,得到一种新型的结构相变材料,其分子式为[CH3CH2-DabcoH][ZnBr4].差示扫描量热法结果显示,化合物在215.13 K左右发生了可逆相变并伴随着5.78 K的热滞后.单晶X射线衍射结果显示,化合物从室温相的Pnma空间群(a=11.446(3)?,b=10.195(3)?,c=12.682(4)?,V=1 480.0(7)?3和Z=4)变化到低温相的P21/c空间群(a=9.99(2)?,b=12.49(3)?,c=11.29(2)?,V=1 406(5)?3和Z=4),发生了结构相变,Dabco环的扭曲及镜面的消失可能是导致相变发生的原因.对化合物进行介电性能测试,在180~223 K的范围内,其介电实部(ε′)有明显的介电转变.

A novel structural phase change material,namely[CH3CH2-DabcoH][ZnBr4]was synthesized under solution method using 1-ethyl-1,4-diazonia-bicyclo[2.2.2]octane and ZnBr2.Differential scanning calorimetry showed that the reversible phase transition occurred at about 215.13 K and accompanied by a thermal lag of 5.78 K.Single crystal X-ray diffraction data suggested that at room temperature phase with the space group of Pnma(a=11.446(3)?,b=10.195(3)?,c=12.682(4)?,V=1480.0(7)?3 and Z=4)transited to a low temperature phase with the space group of P21/c(a=9.99(2)?,b=12.49(3)?,c=11.29(2)?,V=1 406(5)?3 and Z=4),which can be assigned to structural phase transitions.The ordering of twisting motions of Dabco ring and the loss of mirror may drive the phase transition.The dielectric properties of the compounds were tested,and the dielectric real component(ε′)of the compound had a significant dielectric transition over the temperature range of 180 to 223 K.