Reversible Phase Transition of 1,4-Diazoniabicyclo[2.2.2]octane-1-acetate-4-acetic Acid Chloride Trihydrate

1,4-Diazoniabicyclo­[2.2.2]­octane-1-acetate-4-acetic acid forms a complex (<b>1</b>) with chloride ion and water molecule in the ratio 1:1:3. Differential scanning calorimetry (DSC) measurement shows a pair of reversible peaks at 210.7 K (heating) and 180.3 K (cooling) with a large heat hysteresis about 30.4 K, indicating this compound undergoes a reversible structural phase transition. Dielectric measurement further confirms the phase transition. The DSC and dielectric measurements results of its deuterated compound (<b>2</b>) exhibit obvious change compared to those of <b>1</b>. The crystal structures of these two compounds, determined at 153 and 298 K, are all monoclinic in <i>P</i>2₁/<i>n</i>, suggesting the phase transition is isosymmetric. Structural analysis reveals that the changes of the relative location of water molecules and chloride ions affect the formation of different modes of hydrogen-bonded anionic chains, leading to the reversible structural phase transition

Reversible Phase Transition of 1,4-Diazoniabicyclo[2.2.2]octane-1-acetate-4-acetic Acid Chloride Trihydrate

1,4-Diazoniabicyclo­[2.2.2]­octane-1-acetate-4-acetic acid forms a complex (<b>1</b>) with chloride ion and water molecule in the ratio 1:1:3. Differential scanning calorimetry (DSC) measurement shows a pair of reversible peaks at 210.7 K (heating) and 180.3 K (cooling) with a large heat hysteresis about 30.4 K, indicating this compound undergoes a reversible structural phase transition. Dielectric measurement further confirms the phase transition. The DSC and dielectric measurements results of its deuterated compound (<b>2</b>) exhibit obvious change compared to those of <b>1</b>. The crystal structures of these two compounds, determined at 153 and 298 K, are all monoclinic in <i>P</i>2₁/<i>n</i>, suggesting the phase transition is isosymmetric. Structural analysis reveals that the changes of the relative location of water molecules and chloride ions affect the formation of different modes of hydrogen-bonded anionic chains, leading to the reversible structural phase transition

Reversible Phase Transition of 1,4-Diazoniabicyclo[2.2.2]octane-1-acetate-4-acetic Acid Chloride Trihydrate

1,4-Diazoniabicyclo­[2.2.2]­octane-1-acetate-4-acetic acid forms a complex (<b>1</b>) with chloride ion and water molecule in the ratio 1:1:3. Differential scanning calorimetry (DSC) measurement shows a pair of reversible peaks at 210.7 K (heating) and 180.3 K (cooling) with a large heat hysteresis about 30.4 K, indicating this compound undergoes a reversible structural phase transition. Dielectric measurement further confirms the phase transition. The DSC and dielectric measurements results of its deuterated compound (<b>2</b>) exhibit obvious change compared to those of <b>1</b>. The crystal structures of these two compounds, determined at 153 and 298 K, are all monoclinic in <i>P</i>2₁/<i>n</i>, suggesting the phase transition is isosymmetric. Structural analysis reveals that the changes of the relative location of water molecules and chloride ions affect the formation of different modes of hydrogen-bonded anionic chains, leading to the reversible structural phase transition

Reversible Phase Transition of 1,4-Diazoniabicyclo[2.2.2]octane-1-acetate-4-acetic Acid Chloride Trihydrate

1,4-Diazoniabicyclo­[2.2.2]­octane-1-acetate-4-acetic acid forms a complex (<b>1</b>) with chloride ion and water molecule in the ratio 1:1:3. Differential scanning calorimetry (DSC) measurement shows a pair of reversible peaks at 210.7 K (heating) and 180.3 K (cooling) with a large heat hysteresis about 30.4 K, indicating this compound undergoes a reversible structural phase transition. Dielectric measurement further confirms the phase transition. The DSC and dielectric measurements results of its deuterated compound (<b>2</b>) exhibit obvious change compared to those of <b>1</b>. The crystal structures of these two compounds, determined at 153 and 298 K, are all monoclinic in <i>P</i>2₁/<i>n</i>, suggesting the phase transition is isosymmetric. Structural analysis reveals that the changes of the relative location of water molecules and chloride ions affect the formation of different modes of hydrogen-bonded anionic chains, leading to the reversible structural phase transition

Reversible Phase Transition of 1,4-Diazoniabicyclo[2.2.2]octane-1-acetate-4-acetic Acid Chloride Trihydrate

1,4-Diazoniabicyclo­[2.2.2]­octane-1-acetate-4-acetic acid forms a complex (<b>1</b>) with chloride ion and water molecule in the ratio 1:1:3. Differential scanning calorimetry (DSC) measurement shows a pair of reversible peaks at 210.7 K (heating) and 180.3 K (cooling) with a large heat hysteresis about 30.4 K, indicating this compound undergoes a reversible structural phase transition. Dielectric measurement further confirms the phase transition. The DSC and dielectric measurements results of its deuterated compound (<b>2</b>) exhibit obvious change compared to those of <b>1</b>. The crystal structures of these two compounds, determined at 153 and 298 K, are all monoclinic in <i>P</i>2₁/<i>n</i>, suggesting the phase transition is isosymmetric. Structural analysis reveals that the changes of the relative location of water molecules and chloride ions affect the formation of different modes of hydrogen-bonded anionic chains, leading to the reversible structural phase transition

Reversible Phase Transition of 1,4-Diazoniabicyclo[2.2.2]octane-1-acetate-4-acetic Acid Chloride Trihydrate

1,4-Diazoniabicyclo­[2.2.2]­octane-1-acetate-4-acetic acid forms a complex (<b>1</b>) with chloride ion and water molecule in the ratio 1:1:3. Differential scanning calorimetry (DSC) measurement shows a pair of reversible peaks at 210.7 K (heating) and 180.3 K (cooling) with a large heat hysteresis about 30.4 K, indicating this compound undergoes a reversible structural phase transition. Dielectric measurement further confirms the phase transition. The DSC and dielectric measurements results of its deuterated compound (<b>2</b>) exhibit obvious change compared to those of <b>1</b>. The crystal structures of these two compounds, determined at 153 and 298 K, are all monoclinic in <i>P</i>2₁/<i>n</i>, suggesting the phase transition is isosymmetric. Structural analysis reveals that the changes of the relative location of water molecules and chloride ions affect the formation of different modes of hydrogen-bonded anionic chains, leading to the reversible structural phase transition

Solvothermal Syntheses and Physical Properties of Noncentrosymmetric Olefin–Copper(I) Coordination Compounds

Solvothermal reactions of CuX (X = Cl, Br) and the organic olefin ligand 1,3,5-tris­(diallylaminomethyl)-2,4,6-trimethylbenzene (TTB) in the presence of acid offered two novel olefin–copper­(I) coordination compounds with unprecedented CuX cluster structures. The <i>C</i>₃ symmetry of TTB leads to the formation of a novel <i>C</i>₃-symmetric CuX cluster in oligomer compound <b>1</b> (H₃TTB­[Cu₄Cl₃]) and CuX framework in the two-dimensional compound <b>2</b> (H₃TTB­[Cu₈Br₁₁]). However, the flexibility and kink of H₃TTB induce olefin–copper­(I) coordination compounds to crystallize in noncentrosymmetric space groups <i>R</i>3<i>c</i> and <i>R</i>3 for compounds <b>1</b> and <b>2</b>, respectively. In addition to the bowl-like structure of the olefin ligand and <i>C</i>₃-symmetric CuX cluster found in compound <b>1</b>, such bowl-like moieties are connected by another kind of <i>C</i>₃-symmetric CuX cluster to form a novel two-dimensional framework in compound <b>2</b>. The electron cloud distributions and energy levels of the frontier orbitals in both compounds have been calculated by a DFT program. Nonlinear optical property measurement results show that both compounds are second-harmonic generation (SHG) active. Compounds <b>1</b> and <b>2</b> display no phase transition according to the measurement of the temperature dependence of dielectric properties in the temperature range 100–300 K. The close packing and large density from the high CuX/ligand ratio in compound <b>2</b> correspond to the higher dielectric constant

Competitive Halogen Bond in the Molecular Ferroelectric with Large Piezoelectric Response

Molecular piezoelectrics are attracting tremendous interest because of their easy processing, light weight, low acoustical impedance, and mechanical flexibility. However, reports of molecular piezoelectrics with a piezoelectric coefficient <i>d</i>₃₃ comparable to piezoceramics such as barium titanate (BTO, 90–190 pC/N) have been scarce. Here, we present a uniaxial molecular ferroelectric, trimethylchloromethylammonium tribromocadmium­(II) (TMCM-CdBr₃), in which the halogen bonding might be a possible critical point for the stabilization of one-dimensional (1D) {CdBr₃}⁻ chain and further reservation of its ferroelectricity in such organic–inorganic hybrid crystalline systems. It has a large <i>d</i>₃₃ of 139 pC/N, 1 order of magnitude higher than those of most classically uniaxial ferroelectrics such as LiNbO₃ (6–16 pC/N) and Rochelle salt (∼7 pC/N), and comparable with those of multiaxial ferroelectrics such as BTO and trimethylbromomethylammonium tribromomanganese­(II) (112 pC/N). Moreover, the simple single-crystal growth and easy-to-find polar axis enable it to hold a great potential for applying in the single-crystal form. In light of the strong, specific, and directional halogen-bonding interactions, this work provides possibilities to explore new classes of molecular piezoelectrics and contribute to further developments

Reversible Phase Transition of 1,4-Diazoniabicyclo[2.2.2]octane-1-acetate-4-acetic Acid Chloride Trihydrate

1,4-Diazoniabicyclo­[2.2.2]­octane-1-acetate-4-acetic acid forms a complex (<b>1</b>) with chloride ion and water molecule in the ratio 1:1:3. Differential scanning calorimetry (DSC) measurement shows a pair of reversible peaks at 210.7 K (heating) and 180.3 K (cooling) with a large heat hysteresis about 30.4 K, indicating this compound undergoes a reversible structural phase transition. Dielectric measurement further confirms the phase transition. The DSC and dielectric measurements results of its deuterated compound (<b>2</b>) exhibit obvious change compared to those of <b>1</b>. The crystal structures of these two compounds, determined at 153 and 298 K, are all monoclinic in <i>P</i>2₁/<i>n</i>, suggesting the phase transition is isosymmetric. Structural analysis reveals that the changes of the relative location of water molecules and chloride ions affect the formation of different modes of hydrogen-bonded anionic chains, leading to the reversible structural phase transition

Competitive Halogen Bond in the Molecular Ferroelectric with Large Piezoelectric Response

Molecular piezoelectrics are attracting tremendous interest because of their easy processing, light weight, low acoustical impedance, and mechanical flexibility. However, reports of molecular piezoelectrics with a piezoelectric coefficient <i>d</i>₃₃ comparable to piezoceramics such as barium titanate (BTO, 90–190 pC/N) have been scarce. Here, we present a uniaxial molecular ferroelectric, trimethylchloromethylammonium tribromocadmium­(II) (TMCM-CdBr₃), in which the halogen bonding might be a possible critical point for the stabilization of one-dimensional (1D) {CdBr₃}⁻ chain and further reservation of its ferroelectricity in such organic–inorganic hybrid crystalline systems. It has a large <i>d</i>₃₃ of 139 pC/N, 1 order of magnitude higher than those of most classically uniaxial ferroelectrics such as LiNbO₃ (6–16 pC/N) and Rochelle salt (∼7 pC/N), and comparable with those of multiaxial ferroelectrics such as BTO and trimethylbromomethylammonium tribromomanganese­(II) (112 pC/N). Moreover, the simple single-crystal growth and easy-to-find polar axis enable it to hold a great potential for applying in the single-crystal form. In light of the strong, specific, and directional halogen-bonding interactions, this work provides possibilities to explore new classes of molecular piezoelectrics and contribute to further developments