RESUMO
A new strategy for the construction of crystalline molecular rotors is presented. The combination of a conformation-modifiable macrocyclic host and two cooperative guests affords one supramolecular gyroscope-like compound, (t-BuNH3)(18-crown-6)[ZnCl3(H2O)], in which the coordinated water molecule functions as an ultrasmall polar rotator, revealed by its significant dielectric relaxation and the molecular dynamics simulations. In addition, such a compound can reversibly undergo a polar-to-polar phase transition triggered by the changed conformation of the 18-crown-6 host, leading to a switchable on/off rotation of water molecule, well controlled by strength and direction of charge-assisted hydrogen bonds.
RESUMO
An organic-inorganic hybrid compound, [C6H5CH2CH2NH3]2[CdI4], exhibits a reversible ferroelectric phase transition at 301/297 K. Switchable dielectric constant, second harmonic generation, and pyroelectricity were synchronously observed accompanied by the order-disorder phase transition. This finding promotes research on molecular ferroelectrics to search for promising multifunctional switching materials at near room temperature.
RESUMO
The changeable molecular dynamics of flexible polar cations in the variable confined space between inorganic chains brings about a new type of two-step nonlinear optical (NLO) switch with genuine "off-on-off" second harmonic generation (SHG) conversion between one NLO-active state and two NLO-inactive states.