钼基吡啶类有机-无机杂化晶体材料的合成、可逆相变及介电性质

Synthesis,Reversible Phase Transition and Dielectric Properties of Molybdenum⁃Based Pyridines Organic⁃Inorganic Hybrid Crystalline Materials

以钼酸铵、4‑二甲氨基吡啶为原料,在乙醇、甲醇、HBr和水的混合溶液中通过溶剂挥发法成功合成有机-无机杂化晶体材料(C7H11N2)4[MoOBr4(H2O)]2Br2(1)。并通过变温红外光谱、单晶X射线衍射、粉末X射线衍射、热重、介电和差热分析等测试方法对晶体进行结构、热能及电性能表征分析。结构显示阴-阳离子在空间内形成π‑π堆积一维链状和多维氢键网状结构。随着温度的改变以钼配离子[MoOBr4(H2O)]-为顶点的结构空穴变形引起四聚体[MoOBr4(H2O)]2Br2的氢键二面角发生明显折叠摆动,导致化合物1在238 K温度附近产生明显热能同结构相转移以及可逆性介电异常峰。

The organic‑inorganic hybrid crystalline material(C7H11N2)4[MoOBr4(H2O)]2Br2(1)was synthesized by solvent evaporation method in the mixed solution of methanol,ethanol,water and hydrobromic acid using 4‑dimethylaminopyridine and ammonium molybdate as raw materials.The crystal structure,thermal and electrical properties were characterized by infrared spectroscopy,single crystal X‑ray diffraction,powder X‑ray diffraction,thermogravimetric analysis and dielectric measurements and differential thermal analysis.Single crystal X‑ray diffraction displayed one‑dimensional chain and multi‑dimensional hydrogen‑bonding network structure through anions and cations formingπ‑πstacking in space.When the temperature changed,the structural cavity deformation with molybdenum complex ion[MoOBr4(H2O)]-as the vertex caused the hydrogen‑bonding dihedral angles of tetramer[MoOBr4(H2O)]2Br2 to occur obvious folding oscillation,which results in the distinct thermal energy with structural phase transition and reversible dielectric anomaly observed at around 238 K.CCDC:2024338,1⁃LT;2024339,1⁃RT.