crystal data (including checkCIF).rar from Phase transition and switchable dielectric behaviours in an organic–inorganic hybrid compound: (3-nitroanilinium)2(18-crown-6)2(H2PO4)2(H3PO4)3(H2O)

An organic–inorganic hybrid compound with an extensive three-dimensional (3D) crystal structure, (3-nitroanilinium)2(18-crown-6)2(H2PO4)2(H3PO4)3(H2O)(1), was synthesized under slow evaporation conditions. Differential scanning calorimetry measurements indicated that 1 underwent a reversible phase transition at ca 231 K with a hysteresis width of 10 K. Variable-temperature X-ray single-crystal diffraction revealed that the phase transition of 1 can be ascribed to coupling of pendulum-like motions of its nitro group with proton transfer in O–H…O hydrogen bonds of the 3D framework. The temperature dependence of its dielectric permittivity demonstrated a step-like change in the range of 150–280 K with remarkable dielectric anisotropy, making 1 a promising switchable dielectric material. Potential energy calculations further supported the possibility of dynamic motion of the cationic nitro group. Overall, our findings may inspire the development of other switchable dielectric phase transition materials by introducing inorganic anions into organic–inorganic hybrid systems.本研究通过缓慢挥发法合成了一种具有高度延展三维（3D）晶体结构的有机-无机杂化化合物，其化学式为(3-硝基苯胺鎓)₂(18-冠-6)₂(H₂PO₄)₂(H₃PO₄)₃(H₂O)(1)。差示扫描量热法（Differential scanning calorimetry）测试结果表明，化合物1在约231 K处发生可逆相变，热滞宽度为10 K。变温X射线单晶衍射（Variable-temperature X-ray single-crystal diffraction）分析显示，化合物1的相变可归因于其硝基的类摆运动与三维骨架O–H…O氢键体系中的质子转移之间的耦合作用。其介电常数（dielectric permittivity）随温度的变化曲线在150~280 K区间呈现阶跃式变化，且具有显著的介电各向异性，表明化合物1是一种极具应用潜力的可切换介电材料。势能计算（Potential energy calculations）进一步验证了阳离子硝基发生动态运动的可能性。综上，本研究成果可为通过在有机-无机杂化体系中引入无机阴离子来开发新型可切换介电相变材料提供思路与启发。