An Order-Disorder Ferroelectric Host-Guest Inclusion Compound

摘要

The host-guest complex f(DIPA)([18]crown-6)]-(ClO4) (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 centrosym-metric-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 perchlo-rate counterions accompanied by the order-disorder transition of the [18]crown-6 molecules and the anions.