Ordered Matter Science Research Center, Southeast University, Nanjing 211189 (P.R. China).
Angew Chem Int Ed Engl. 2014 Feb 17;53(8):2114-8. doi: 10.1002/anie.201307690. Epub 2014 Feb 4.
The host-guest complex (DIPA)([18]crown-6) (1; DIPA=2,6-diisopropylanilinium) was constructed and found to undergo a sequence of phase transitions (Ibam-Pbcn-Pna21) at T1=278 K and T2=132 K, respectively. Systematic characterizations, such as differential scanning calorimetry, heat capacity, temperature-dependent dielectric constant, and P-E hysteresis loop, reveal that the centrosymmetric-to-polar phase transition at T2 is a paraelectric-to-ferroelectric transition. The symmetry breaking was also confirmed by temperature-dependent second-harmonic generation effect and X-ray powder diffraction. The ferroelectric mechanism is attributable to the linear motion of the perchlorate counterions accompanied by the order-disorder transition of the [18]crown-6 molecules and the anions.
(DIPA)([18]冠-6) (1) (DIPA=2,6-二异丙基苯胺鎓)主体-客体配合物被构建出来，并发现其在 T1=278 K 和 T2=132 K 处分别经历了一系列相变（Ibam-Pbcn-Pna21）。系统的特性研究，如差示扫描量热法、热容、温度依赖介电常数和 P-E 滞后回线，表明 T2 处的非中心对称到极性相变是顺电到铁电的转变。对称破缺也通过温度依赖的二次谐波产生效应和 X 射线粉末衍射得到了证实。铁电机制归因于高氯酸根阴离子的线性运动，同时伴随着[18]冠-6 分子和阴离子的有序-无序转变。
