高低介电态的电学双稳态超分子相变介电材料的制备与表征

One new organic-inorganic hybrid supramolecular complex [(TAP-NH3)?(18-crown- 6)?0.5(H2O)]?2(ClO4-) (TAPC) with electrical bistability has been successfully obtained by reaction between 4-amino-2,2,6,6-tetramethylpiperidine (TAP-NH3), HClO4 and 18-crown-6. The complex was characterized by element analysis, variable-temperature X-ray single-crystal diffraction analysis, TG, DSC, powder XRD and temperature-dependent dielectric measurement. X-ray single-crystal analysis reveals that complex 1 (TAPC) belongs to monoclinic system, space group P21/m at both room and high temperature. Complex 1 is a switchable dielectric material with electrical bistability. The –NH3+ nests in the 18-crown-6 ring to form a supramolecular rotator-stator-like structure.The order–disorder transition of the ClO4- anions and the relative displacement of the guest molecule H2O are not only the significant difference in structures at different temperatures, but also the two main factors contributing to this reversible first-order phase transition at high temperature. This result has also been verified by a pair of strong peaks in the DSC measurement and a large thermal hysteresis at 37.2 K.