Double-resonance magic angle coil spinning

We present an extension of magic angle coil spinning (MACS) solid-state NMR spectroscopy to double-resonance experiments, enabling implementation of powerful double-resonance solid-state NMR methodologies including cross polarization, proton decoupling, and two-dimensional correlation spectroscopy etc., while still enjoying the merits that are intrinsic to MACS, such as high concentration sensitivity, eliminated magnetic susceptibility-induced field distortion, and an easy-to-use approach with the conventional and widespread hardware

Glass-phase coordination polymer displaying proton conductivity and guest-accessible porosity

We describe the preparation of the crystalline and glassy state of a coordination polymer displaying proton conduction and guest-accessible porosity. EXAFS and solid-state NMR analyses indicated that pyrophosphate and phosphate ions are the main proton transporters in the glass and that homogeneously distributed 5-chloro-1H-benzimidazole in the glass provide the porosity

Order-to-disorder structural transformation of a coordination polymer and its influence on proton conduction.

Accepted 14 Jul 2014.We observed an ordered-to-disordered structural transformation in a Cu(2+) coordination polymer and investigated its influence on the proton conductivity. The transformation generated highly mobile proton carriers in the structure. The resulting material exhibited a conductivity greater than 10(-2) S cm(-1) at 130 °C. The structural transformation and the conduction mechanism were investigated by EXAFS, TPD-MS and NMR

Probing dynamics of carbon dioxide in a metal-organic framework under high pressure by high-resolution solid-state NMR

The application of high-resolution NMR analysis for CO2 adsorbed in an MOF under high pressure is reported for the first time. The results showed that CO2 adsorbed in MOF-74 had a unusual slow mobility (τ ~ 10-8 s). CO2–CO2 interactions suppressed the mobility of CO2 under high pressure, which, in turn, would have contributed to the stability of CO2 at adsorption sites

Template-directed proton conduction pathways in a coordination framework

We present a strategy for creating coordination frameworks exhibiting proton conduction with thermal stability. The coordination framework, where template cations link 1-D chains via hydrogen bonds, has dynamic hydrogen bond networks where protons move without water support. Solid-state NMR and X-ray studies visualized the proton hopping mechanism, and revealed that the templates provide the bridging of the 1-D chains to attain proton conduction. The templates also enable the proton conductive networks to be maintained at 190 °C through multiple interactions between the templates and the 1-D chains

Mixing of immiscible polymers using nanoporous coordination templates

混ざり合わないポリマーを完全に混ぜる手法を開発 -プラスチックの持つ機能を飛躍的に向上-. 京都大学プレスリリース. 2015-07-02.The establishment of methodologies for the mixing of immiscible substances is highly desirable to facilitate the development of fundamental science and materials technology. Herein we describe a new protocol for the compatibilization of immiscible polymers at the molecular level using porous coordination polymers (PCPs) as removable templates. In this process, the typical immiscible polymer pair of polystyrene (PSt) and poly(methyl methacrylate) (PMMA) was prepared via the successive homopolymerizations of their monomers in a PCP to distribute the polymers inside the PCP particles. Subsequent dissolution of the PCP frameworks in a chelator solution affords a PSt/PMMA blend that is homogeneous in the range of several nanometers. Due to the unusual compatibilization, the thermal properties of the polymer blend are remarkably improved compared with the conventional solvent-cast blend. This method is also applicable to the compatibilization of PSt and polyacrylonitrile, which have very different solubility parameters

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

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