三维氢键型金属-有机化合物[H_(2)(dabco)]_(2)[Co(NCS)_(4)]_(2)·4H_(2)O的合成和性能表征

Synthesis and Properties Characterization of Three-dimensional Hydrogen Bonding Metal-organic Compound[H_(2)(dabco)]_(2)[Co(NCS)_(4)]_(2)·4H_(2)O

以1,4-二氮杂二环[2.2.2]辛烷(dabco)、氯化钴和硫氰化钾为原料,水、甲醇和盐酸为混合溶剂,蒸发获得一种三维氢键型金属-有机化合物[H_(2)(dabco)]_(2)[Co(NCS)_(4)]_(2)·4H_(2)O(1)。通过单晶X射线衍射、红外光谱、元素分析、粉末X射线衍射、热重分析、差示扫描量热法、介电和铁电等测试对其结构、热学性能与电学性能进行表征。结构显示[H_(2)(dabco)]_(2)[Co(NCS)_(4)]_(2)·4H_(2)O从低温极性空间群P21转化为中心空间群P nma,[H 2dabco]2+阳离子发生有序-无序超分子转动,导致在200 K附近呈现极性-非极性相变及阶梯型介电异常,获得一种顺电相-铁电相可逆的铁电功能材料。

A three-dimensional hydrogen bonding supramolecular compound[H_(2)(dabco)]_(2)[Co(NCS)_(4)]_(2)·4H_(2)O(1),was synthesized by solvent evaporation in the mixed solution of methanol,hydrochloric acid and water with 1,4-diazabicyclo[2.2.2]octane,CoCl_(2)·6H_(2)O and KSCN.The structure,thermal energy and electrical properties of the crystal were characterized by single crystal X-ray diffraction,infrared spectroscopy,elemental analysis,powder X-ray diffraction,thermogravimetric analysis,differential scanning calorimetry,dielectric constant and ferroelectricity test.The compound underwent a reversible structural phase transition at around 200 K.The structure showed that[H_(2)(dabco)]_(2)[Co(NCS)_(4)]_(2)·4H_(2)O transformed from cold polar space group P2_(1) to central space group P nma.[H_(2)dabco]^(2+) cations displayed order-disordered supramolecular rotations,leading to a polar-non-polar phase transition and step-type dielectric anomaly occurred near 200 K,obtaining a reversible ferroelectric functional material with paraelectric and ferroelectric phases.