Designing dynamic coordination bonds in polar hybrid crystals for a high-temperature ferroelastic transition.

Ferroelastic materials have gained widespread attention as promising candidates for mechanical switches, shape memory, and information processing. Their phase-transition mechanisms usually originate from conventional order-disorder and/or displacive types, while those involving dynamic coordination bonds are still scarce. Herein, based on a strategic molecular design of organic cations, we report three new polar hybrid crystals with a generic formula of AA'RbBiCl (A = A' = MeSO for 1; A = MeSO and A' = MeN for 2; A = A' = MeNNH for 3).

A hybrid double perovskite ferroelastic exhibiting the highest number of orientation states.

Integrating NH as a B'-site ion within a three-dimensional double hybrid perovskite resulted in a novel high-temperature ferroelastic, (MeNOH)(NH)[Co(CN)], which uniquely demonstrates a reversible triclinic-to-cubic phase transition at 369 K and offers a record-setting 24 orientation states, the highest ever reported among all ferroelastics.

Molecular Design of a Metal-Nitrosyl Ferroelectric with Reversible Photoisomerization.

The development of photo-responsive ferroelectrics whose polarization may be remotely controlled by optical means is of fundamental importance for basic research and technological applications. Herein, we report the design and synthesis of a new metal-nitrosyl ferroelectric crystal (DMA)(PIP)[Fe(CN)(NO)] () (DMA = dimethylammonium, PIP = piperidinium) with potential phototunable polarization via a dual-organic-cation molecular design strategy. Compared to the parent non-ferroelectric (MA)[Fe(CN)(NO)] (MA = methylammonium) material with a phase transition at 207 K, the introduction of larger dual organic cations both lowers the crystal symmetry affording robust ferroelectricity and increases the energy barrier of molecular motions, endowing with a large polarization of up to 7.

An unprecedented hexagonal double perovskite organic-inorganic hybrid ferroelastic material: (piperidinium)[KBiCl].

An unprecedented A2MIMIIIX6-type double perovskite adopting a fully hexagonal BaNiO3-type structure, (piperidinium)2[KBiCl6], undergoes a 2/mF1[combining macron] ferroelastic phase transition at 285 K with a spontaneous strain of 0.0615, arising from the order-disorder transition of organic cations together with the synchronous displacement of inorganic chains.

Accuracy of dynamic navigation in implant surgery: A systematic review and meta-analysis.

Objective: To assess the accuracy of dynamic computer-assisted implant surgery.

Materials And Methods: An electronic search up to March 2020 was conducted using PubMed, Embase, and the Cochrane Central Register of Controlled Trial to identify studies using dynamic navigation in implant surgery, and additional manual search was performed as well. Clinical trials and model studies were selected.

Photoresponsive Organic-Inorganic Hybrid Ferroelectric Designed at the Molecular Level.

Molecular ferroelectrics are becoming an important area of research due to their ability to form a variety of structures exhibiting the desired properties. However, the precise control over the assembly of molecular building blocks for the design and synthesis of photoresponsive molecular ferroelectrics remains a considerable challenge. Here, we report a new hybrid high-temperature ferroelectric, (MeNH)[NaFe(CN)(NO)], by judiciously assembling inorganic photochromic nitroprusside anion, as the framework building block, and polar organic cation MeNH, as the dipole-moment carrier, into the crystal lattice.

A large room-temperature entropy change in a new hybrid ferroelastic with an unconventional bond-switching mechanism.

We showed a reversible bond-switching ferroelastic phase transition at near room temperature in a novel organic-inorganic hybrid, (MeNNH)[Co(CN)Na(HO)], to afford a latent heat of 43.7 kJ kg and a large entropy change of 146 J K kg.

Nitroprusside as a promising building block to assemble an organic-inorganic hybrid for thermo-responsive switching materials.

We present a new hybrid compound, namely (Me2NH2)[KFe(CN)5(NO)], possessing a unique nitroprusside-based inorganic host framework in 4-connected sra topology encapsulating organic guest cations. The flexible host-guest hydrogen bonds and synchronously deformed inorganic framework give rise to thermal-responsive switching behaviours on both thermal expansion and nonlinear optical properties during the phase transition at around room temperature.

Switching hydrogen bonds to readily interconvert two room-temperature long-term stable crystalline polymorphs in chiral molecular perovskites.

It is challenging to endow polymorphs with both long-term stability and easy interconvertibility. We demonstrate an interesting example that two room-temperature polymorphs could be long-term stable yet easily interconvertible, at a pressure of ∼4.8 MPa and a temperature of 120 °C, by switching hydrogen bonds via collective reorientation of organic cations in chiral molecular perovskites.

A new ferroelastic hybrid material with a large spontaneous strain: (MeNOH)[ZnCl].

A new hybrid compound (MeNOH)[ZnCl] undergoes an above-room-temperature mmmF2/m ferroelastic phase transition and exhibits a large spontaneous strain of 0.129, owing to an order-disorder transition of organic cations.

Room-temperature optic-electric duple bistabilities induced by plastic transition.

We disclosed that acetamidinium perchlorate is a plastic crystal undergoing a near-room-temperature plastic transition. Thanks to drastic symmetry breaking during the plastic transition, it displays remarkable nonlinear optical switching with a high on/off contrast and a superior reversibility, as well as rapid dielectric switching between the high and low dielectric states.

A Molecular Perovskite with Switchable Coordination Bonds for High-Temperature Multiaxial Ferroelectrics.

The underlying phase transitions of ferroelectric mechanisms in molecular crystals are mainly limited to order-disorder and displacive types that are not involved in breaking of the chemical bonds. Here, we show that the bond-switching transition under ambient pressure is designable in molecular crystals, and demonstrate how to utilize the weaker and switchable coordination bonds in a novel molecular perovskite, [(CH)NOH][KFe(CN)] (TMC-1), to afford a scarce multiaxial ferroelectrics with a high Curie temperature of 402 K and 24 equivalent ferroelectric directions (more than BaTiO). The high-quality thin films of TMC-1 can be easily fabricated by a simple solution process, and to reveal perfect ferroelectric properties at both macroscopic and microscopic scales, suggesting TMC-1 as a promising candidate for applications in next-generation flexible electronics.

Zeolite CAN and AFI-Type Zeolitic Imidazolate Frameworks with Large 12-Membered Ring Pore Openings Synthesized Using Bulky Amides as Structure-Directing Agents.

Using bulky amides as the structure-directing agents (SDAs) is an alternative synthetic strategy for the exploration of crystalline large pore (≥12-membered ring) zeolitic imidazolate frameworks (ZIFs). Specifically, by using the bulky amides, dibutylformamide (DBF) and dipropylformamide (DPF) as solvent and imidazole (Im) as a ligand, two ZIFs mimicking the CAN and AlPO-5 (AFI) zeotypes with 12-membered ring (MR) pore openings were synthesized, and denoted as CAN-[Zn(Im)] and AFI-[Zn(Im)], respectively. These two materials are the first known examples of Zn(Im) polymorphs with 12-MR pores and AFI-[Zn(Im)] has the largest pore apertures reported to date for ZIF materials.

Plastic Crystals with Polar Halochromate Anion: Thermosensitive Dielectrics Based upon Plastic Transition and Dipole Rotation.

Plastic crystals functioning with rotatable components offer new opportunities in areas such as modern optoelectronic materials. Here, by taking advantage of controllable rotation of the polar component within the ion-pair plastic-crystal system, we present two such crystals, namely, (EtN)(CrOX) (X = Cl or Br), which are unusual examples exhibiting two-staged thermosensitive dielectric responses above room temperature. The frequency-dependent response in the first stage is due to the structural phase transitions, whereas that in the second stage is induced by dynamic rotation of the polar halochromate anions in their NaCl-type plastic-crystal phases.

Synthesis of Copolymers by Living Carbanionic Alternating Copolymerization.

The synthesis and characterization of copolymers from styrene and 1,3-pentadiene (two isomers) are reported. Styrene/1,3-pentadiene (1:1) copolymerization with carbanion initiator yield living, well-defined, alternating (r1 = 0.037, r2 = 0.

The cation-dependent structural phase transition and dielectric response in a family of cyano-bridged perovskite-like coordination polymers.

A family of cyano-bridged perovskite-like coordination polymers (CPs), [(CH3)nNH(4-n)]2[KFe(CN)6] (n = 1 (1), 2 (2), 3 (3), and 4 (4)), were synthesized and characterized. The differential scanning calorimetry measurements and variable-temperature single-crystal X-ray structural analyses revealed that, owing to the deformation of the host framework as well as the dynamic transition of the guest cation between the static/ordered and dynamic/disordered states, the four CPs undergo structural phase transitions (at 429, 226, 316, and 350 K, respectively) with the symmetry breakings dependent on the symmetries of the encapsulated guest cations. The modulated differential scanning calorimetry measurement suggested that the phase transitions of 1 and 3 have more striking kinetic processes related to their drastic deformation of the host framework as well as a very significant alteration of the host-guest interaction during the phase transition.

Restraining the motion of a ligand for modulating the structural phase transition in two isomorphic polar coordination polymers.

A structural phase transition induced by ligand motion was found in a new polar coordination polymer: [Cu(NCS)2(4-APy)2]n (4-APy = 4-aminopyridine). Restraining such motion in an isomorphic compound [Cu(NCS)2(4-MeAPy)2]n (4-MeAPy = 4-methylaminopyridine) results in distinct phase transition behaviour. These findings provide a new clue for modulating phase transition behaviour in known materials.

Optimization of submerged fermentation of Thelephora ganbajun zang.

The effects of the fermentation conditions on both the biomass yield and the organic selenium yield of Thelephora ganbajun zang were studied. The components most suitable for the submerged fermentation medium were examined using the orthogonal array method; they comprised sucrose at 30 g L(-1) , carbamide 1 g L(-1) , corn steep liquor 8 g L(-1) , MgSO4 ·7H2 O 0.3 g L(-1) , KH2 PO4 0.