ABSTRACT
A novel organic-inorganic ABX3 perovskite-type material with specific hydrogen bonding interactions, N,N-dimethylethanolammonium trichlorocadmate ([DMEA]CdCl3), has been synthesized as a phase transition material. It is notable that the DMEA cations are arranged to form one-dimensional chains connected by hydrogen bonds at room temperature, which are very sparse in other perovskite-type compounds. The strong intermolecular interactions have made the phase transition temperature of the material reach up to 429 K, as confirmed by differential scanning calorimetry measurements, variable-temperature structural analyses, and dielectric measurements. The origin of the symmetry-breaking phase transition is associated with the motion or reorientation of the DMEA cations, accompanied by the crystal structures from orthorhombic Pnma to monoclinic P21/c with the temperature decreases. The finding of [DMEA]CdCl3 with unprecedented hydrogen bonding interactions has opened a new avenue to design novel phase transition materials with higher transition temperatures.
ABSTRACT
[C6N2H18][SbI5] (1), a novel metal halide semiconductor with dielectric relaxation behavior, has been successfully synthesized, in which the cavities between the one-dimensional [SbI5] n2- polyanions are occupied by 2-methyl-1,5-pentanediammonium (2-MPDA) cations. 1 undergoes a reversible solid-state phase transition at TC = 192.7 K and shows a step-like dielectric anomaly. Interestingly, above TC, distinct dielectric dispersion in a wide temperature range is also witnessed. Remarkably, the solid state UV-vis diffuse reflectance spectrum of 1 exhibits a slightly gentler absorption edge at about 650 nm; that is, 1 adopts an indirect band gap with 1.92 electron volts. The combined narrow band gap, strong photoconductivity effect, and excellent dielectric relaxation might shed light on the exploitation of lead-free hybrid metal halide molecular materials with promising application prospects in thermoresponsive relaxation-type dielectric materials and photovoltaic conversion devices.
ABSTRACT
Piezoelectric materials are a class of important functional materials applied in high-voltage sources, sensors, vibration reducers, actuators, motors, and so on. Herein, [(CH3 )3 S]3 [Bi2 Br9 ](1) is a brilliant semiconducting organic-inorganic hybrid perovskite-type non-ferroelectric piezoelectric with excellent piezoelectricity. Strikingly, the value of the piezoelectric coefficient d33 is estimated as ≈18â pC N-1 . Such a large piezoelectric coefficient in non-ferroelectric piezoelectric has been scarcely reported and is comparable with those of typically one-composition non-ferroelectric piezoelectrics such as ZnO (3pC N-1 ) and much greater than those of most known typical materials. In addition, 1 exhibits semiconducting behavior with an optical band gap of ≈2.58â eV that is lower than the reported value of 3.37â eV for ZnO. This discovery opens a new avenue to exploit molecular non-ferroelectric piezoelectric and should stimulate further exploration of non-ferroelectric piezoelectric due to their high stability and low loss characteristics.
ABSTRACT
An organic-inorganic hybrid compound, [NH3(CH2)5NH3]SbCl5, exhibits a switchable second harmonic generation (SHG) effect between SHG-OFF and SHG-ON states and tunable dielectric behaviors between high and low dielectric states, connected with the changes in the dynamics of 1,5-pentanediammonium cations during its centrosymmetric-to-noncentrosymmetric symmetry breaking phase transition at 365.4 K.
ABSTRACT
A layered organic-inorganic hybrid compound, tetra(cyclopentylammonium) decachlorotricadmate(II) (1), in which the two-dimensional [Cd3Cl10](4-)n networks built up from three face-sharing CdCl6 octahedra are separated by cyclopentylammonium cation bilayers, has been discovered as a new phase transition material. It undergoes two successive structural phase transitions, at 197.3 and 321.6 K, which were confirmed by differential scanning calorimetry measurements, variable-temperature structural analyses, and dielectric measurements. The crystal structures of 1 determined at 93, 298, and 343 K are solved in P212121, Pbca, and Cmca, respectively. A precise analysis of the structural differences between these three structures reveals that the origin of the phase transition at 197.3 K is ascribed to the order-disorder transition of the cyclopentylammonium cations, while the phase transition at 321.6 K originates from the distortion of the two-dimensional [Cd3Cl10](4-)n network.
ABSTRACT
In the title compound, C(19)H(15)Cl(2)O(2)P, the dihedral angle between the mean planes of the phenyl rings bonded to the P atom is 75.4â (1)°. In the crystal, mol-ecules are linked into chains running along the a axis by inter-molecular O-Hâ¯O hydrogen bonds. Mol-ecules are further connected into a three-dimensional array by weak C-Hâ¯O inter-actions.
ABSTRACT
In the title compound, C(19)H(16)NO(4)P, the dihedral angle between the mean planes of the phenyl rings bonded to the P atom is 75.4â (1)°. In the crystal, mol-ecules are linked into chains running along the a axis by inter-molecular O-Hâ¯O hydrogen bonds. Mol-ecules are further connected into a three-dimensional array by weak C-Hâ¯O hydrogen bonds.
ABSTRACT
The title compound, [Ni(2)(C(7)H(5)O(2))(4)(C(7)H(6)O(2))(2)], is composed of two Ni(II) ions, four bridging benzoate anions and two η(1)-benzoic acid mol-ecules. The [Ni(2)(PhCOO)(4)] unit adopts a typical paddle-wheel conformation. The center between the two Ni(II) atoms represents a crystallographic center of inversion. In addition, each Ni(II) ion also coordinates to one O atom from a benzoic acid mol-ecule. The crystal packing is realised by inter-molecular hydrogen-bonding inter-actions and π-π stacking inter-actions, with a centroid-centroid distance of 3.921â (1)â Å.
ABSTRACT
The title compound, C(14)H(6)O(7)·C(10)H(8)N(2), has been hydro-thermally synthesized. Structural ananlysis indicates that the crystals are produced by cocrystallization of naphthalene-1,4,5,8-tetra-carboxylic acid 1,8-anhydride and 4,4'-bipyridine (bpy) mol-ecules. The crystal packing is stabilized by inter-molecular O-Hâ¯N and C-Hâ¯O hydrogen bonds and π-π stacking inter-actions [centroid-centroid distances = 3.5846â (9)â Å].
