Polar Molecule-Based Material with Optic–Electric Switching Constructed by Polar Anions

Abstract

Polar crystal structures have attracted more and more attention, due to their unique characteristics, such as ferroelectricity, piezoelectricity, and nonlinear optical property, etc. However, the construction of polar materials is always accidental, and finding an effective synthesis strategy to construct polar materials remains a challenge. Herein, inorganic–organic hybrid compounds of [C7H14N]­[FeCl4] (1) ([C7H14N] = quinuclidinium cation) and [C7H14N]­[GeCl3] (2) were prepared, respectively, to verify the beneficial effect of polar anions on the construction of polar crystals. Compound 1 crystallized in the Pbca space group, while 2 belongs to the P43 space group at room temperature. Investigation into the structure of 2 reveals that the polarity of 2 derives from the triangular pyramid structure of [GeX3]− with lone pair electrons. Meanwhile, 2 undergoes a phase transition from the P43 space group to the center Pm m at 385 K, leading to the optic–electric switching property. Thus, the present work exhibits the advantage of [GeX3]− as the inorganic constituent component in the hybrid polar materials and provides an effective approach for the construction of a polar molecule-based crystal with a switchable property.

((R)-(−)-3-Hydroxyquinuclidium)[FeCl4]; a plastic hybrid compound with chirality, ferroelectricity and long range magnetic ordering

“…SR-XRPD data from 260 to 365 K were refined using the pattern matching method with the FullProf suite program. 33 The evolution of the crystal parameters and cell volume of phase II and III SR-XRPD is shown in Fig. 6.…”

“…30 Inspired by these works, we have selected the modified globular quinuclidine molecule, (R)-(À)-3-hydroxyquinuclidine, which presents an additional OH group, in order to reduce the molecular symmetry and introduce chirality in the quinuclidinium tetrachlorideferrate compound. [31][32][33] Thus, a new halometallate compound, ((R)-(À)-3-hydroxyquinuclidium)[FeCl 4 ] was synthetized. The use of this homochiral cation can help in achieving a ferroelectric compound.…”

Plasticity and Ferroelasticity Transitions of Molecular Complex [(C4H9N2)2][Fe3O(O2CH)9] on Heating and Cooling near Room Temperature

“…The molecular-ionic compound with molecular building blocks instead of elemental ions in pure inorganic compounds is a potential system in developing multiple rotor phase transition materials . In those compounds, noncovalent interactions such as hydrogen bonding, π–π stacking, and CH−π interactions contact the anions and cations and collaborate toward the stimulus response .…”

“…The molecular nature makes it easy to regulate the composition and structure of those compounds by changing the counter-ionic component . In the reported molecular-ionic compounds with phase transition, anions are simple mononuclear components, i.e., MX 4 and MO 3 X, and thus, the major attention of researchers has focused on exploring the motion of cations. , With polynuclear components as anions, responses of anions to stimuli may lead to additional structural changes but are rarely reported …”

Near-Infrared Phosphorescent Hybrid Organic–Inorganic Perovskite with High-Contrast Dielectric and Third-Order Nonlinear Optical Switching Functionalities

“…Thus far, switchable dielectric properties were reported mainly for metal halides, 3 , 7 , 29 , 32 − 34 but compounds with other linkers, for instance, perchlorate or thiocyanate, are also known. 30 , 34 Most of the discovered compounds present isolated metal–ligand clusters, not beneficial for optical properties.…”