Red-to-Black Piezochromism in a Compressible Pb–I–SCN Layered Perovskite

Red-to-Black Piezochromism in a Compressible Pb–I–SCN Layered Perovskit

Red-to-Black Piezochromism in a Compressible Pb–I–SCN Layered Perovskite

Red-to-Black Piezochromism in a Compressible Pb–I–SCN Layered Perovskit

Integration of Intrinsic Proton Conduction and Guest-Accessible Nanospace into a Coordination Polymer

We report the synthesis and characterization of a coordination polymer that exhibits both intrinsic proton conductivity and gas adsorption. The coordination polymer, consisting of zinc ions, benzimidazole, and orthophosphate, exhibits a degree of flexibility in that it adopts different structures before and after dehydration. The dehydrated form shows higher intrinsic proton conductivity than the original form, reaching as high as 1.3 × 10^–3 S cm^–1 at 120 °C. We found that the rearranged conduction path and liquid-like behavior of benzimidazole molecules in the channel of the framework afforded the high proton conductivity. Of the two forms of the framework, only the dehydrated form is porous to methanol and demonstrates guest-accessible space in the structure. The proton conductivity of the dehydrated form increases by 24 times as a result of the in situ adsorption of methanol molecules, demonstrating the dual functionality of the framework. NMR studies revealed a hydrogen-bond interaction between the framework and methanol, which enables the modulation of proton conductivity within the framework

Coordination-Network-Based Ionic Plastic Crystal for Anhydrous Proton Conductivity

An ionic coordination network consisting of protonated imidazole and anionic one-dimensional chains of Zn²⁺ phosphate was synthesized. The compound possesses highly mobile ions in the crystal lattice and behaves as an ionic plastic crystal. The dynamic behavior provides a proton conductivity of 2.6 × 10^–4 S cm^–1 at 130 °C without humidity

Reversible Solid-to-Liquid Phase Transition of Coordination Polymer Crystals

The solid-to-liquid phase transition, a fundamental process commonly observed for various types of substances with significant potential for application, has been given little attention in the field of coordination polymers (CPs) despite the rich functionality of these compounds. In this article, we report the reversible solid-to-liquid phase transition of crystalline CPs. These CPs are composed of zinc ions, phosphate, and azoles, and a well-balanced composition, ionicity, and bond strength afford “melting” CPs. We examined the structure of one such melting framework in the liquid and glass states and found that the coordination bonds are not fully preserved in the liquid state but are re-formed in the glass state. As a demonstration, we fabricated, via phase transition, a thin film with an aligned crystal orientation and a monolith crystal of the CP

Inherent Proton Conduction in a 2D Coordination Framework

We synthesized a coordination polymer consisting of Zn²⁺, 1,2,4-triazole, and orthophosphates, and demonstrated for the first time intrinsic proton conduction by a coordination network. The compound has a two-dimensional layered structure with extended hydrogen bonds between the layers. It shows intrinsic proton conductivity along the direction parallel to the layers, as elucidated by impedance studies of powder and single crystals. From the low activation energy for proton hopping, the conduction mechanism was found to be of the Grotthuss fashion. The hopping is promoted by rotation of phosphate ligands, which are aligned on the layers at appropriate intervals

Postsynthesis Modification of a Porous Coordination Polymer by LiCl To Enhance H⁺ Transport

A Ca²⁺ porous coordination polymer with 1D channels was functionalized by the postsynthesis addition of LiCl to enhance the H⁺ conductivity. The compound showed over 10^–2 S cm^–1 at 25 °C and 20% relative humidity. Pulse-field gradient NMR elucidated that the fast H⁺ conductivity was achieved by the support of Li⁺ ion movements in the channel

Synthesis and Porous Properties of Chromium Azolate Porous Coordination Polymers

We developed a new route for synthesis of Cr-based porous coordination polymers (PCPs) with azole ligands and characterized the unique open structures by single-crystal X-ray studies and other spectroscopy techniques. Chromium-based PCPs have been prepared from azolate ligands 3,5-dimethyl-1<i>H</i>-pyrazole-4-carboxylic acid (H₂dmcpz) and 1,4-di­(1<i>H</i>-tetrazole-5yl)­benzene (H₂BDT) by solvothermal reactions under an Ar atmosphere. [Cr₃O­(Hdmcpz)₆(DMF)₃]⊃DMF (<b>1</b>⊃DMF) is a coordination compound that forms a hydrogen-bonded porous network. [Cr₃O­(HBDT)₂(BDT)­Cl₃)]⊃DMF (<b>2</b>⊃DMF) possesses a new type of trinuclear chromium μ₃-O unit cluster and the novel topology of a Cr-based PCP with 700 m² g^–1 of Brunauer–Emmett–Teller surface area. [Cr­(BDT)­(DEF)]⊃DEF (<b>3</b>⊃DEF) is structurally flexible and reactive to O₂ molecules because of the unsaturated Cr²⁺ centers. This is the first report of a Cr-based PCP/metal–organic framework with noncarboxylate ligands and characterization by single-crystal X-ray diffraction

Synthesis and Porous Properties of Chromium Azolate Porous Coordination Polymers

We developed a new route for synthesis of Cr-based porous coordination polymers (PCPs) with azole ligands and characterized the unique open structures by single-crystal X-ray studies and other spectroscopy techniques. Chromium-based PCPs have been prepared from azolate ligands 3,5-dimethyl-1<i>H</i>-pyrazole-4-carboxylic acid (H₂dmcpz) and 1,4-di­(1<i>H</i>-tetrazole-5yl)­benzene (H₂BDT) by solvothermal reactions under an Ar atmosphere. [Cr₃O­(Hdmcpz)₆(DMF)₃]⊃DMF (<b>1</b>⊃DMF) is a coordination compound that forms a hydrogen-bonded porous network. [Cr₃O­(HBDT)₂(BDT)­Cl₃)]⊃DMF (<b>2</b>⊃DMF) possesses a new type of trinuclear chromium μ₃-O unit cluster and the novel topology of a Cr-based PCP with 700 m² g^–1 of Brunauer–Emmett–Teller surface area. [Cr­(BDT)­(DEF)]⊃DEF (<b>3</b>⊃DEF) is structurally flexible and reactive to O₂ molecules because of the unsaturated Cr²⁺ centers. This is the first report of a Cr-based PCP/metal–organic framework with noncarboxylate ligands and characterization by single-crystal X-ray diffraction

Postsynthesis Modification of a Porous Coordination Polymer by LiCl To Enhance H⁺ Transport

A Ca²⁺ porous coordination polymer with 1D channels was functionalized by the postsynthesis addition of LiCl to enhance the H⁺ conductivity. The compound showed over 10^–2 S cm^–1 at 25 °C and 20% relative humidity. Pulse-field gradient NMR elucidated that the fast H⁺ conductivity was achieved by the support of Li⁺ ion movements in the channel