Eutectic CsHSO4-Coordination Polymer Glasses with Superprotonic Conductivity.

Superprotonic phase transition in CsHSO4 allows fast protonic conduction, but only at temperatures above the transition temperature of 141 °C (Tc). Here, we preserve the superprotonic conductivity of CsHSO4 by forming a binary CsHSO4-coordination polymer glass system, showing eutectic melting. Their anhydrous proton conductivities below Tc are at least 3 orders of magnitude higher than CsHSO4 without compromising conductivity at higher temperatures or the need for humidification, reaching 6.3 mS cm-1 at 180 °C. The glass also introduces processability to the conductor, as its viscosity below 103 Pa·s can be achieved at 65 °C. Solid-state NMR and X-ray pair distribution functions reveal the oxyanion exchanges and the origin of the preserved conductivity. Finally, we demonstrate the preparation of a micrometer-scale thin-film proton conductor showing low resistivity with high transparency (transmittance >85% between 380-800 nm).

Rhodium-Organic Cuboctahedra as Porous Solids with Strong Binding Sites.

The upbuilding of dirhodium tetracarboxylate paddlewheels into porous architectures is still challenging because of the inertness of equatorial carboxylates for ligand-exchange reaction. Here we demonstrate the synthesis of a new family of metal-organic cuboctahedra by connecting dirhodium units through 1,3-benzenedicarboxylate and assembling cuboctahedra as porous solids. Carbon monoxide and nitric oxide were strongly trapped in the internal cavity thanks to the strong affinity of unsaturated axial coordination sites of dirhodium centers.

Shape-memory nanopores induced in coordination frameworks by crystal downsizing.

Flexible porous coordination polymers change their structure in response to molecular incorporation but recover their original configuration after the guest has been removed. We demonstrated that the crystal downsizing of twofold interpenetrated frameworks of [Cu(2)(dicarboxylate)(2)(amine)](n) regulates the structural flexibility and induces a shape-memory effect in the coordination frameworks. In addition to the two structures that contribute to the sorption process (that is, a nonporous closed phase and a guest-included open phase), we isolated an unusual, metastable open dried phase when downsizing the crystals to the mesoscale, and the closed phase was recovered by thermal treatment. Crystal downsizing suppressed the structural mobility and stabilized the open dried phase. The successful isolation of two interconvertible empty phases, the closed phase and the open dried phase, provided switchable sorption properties with or without gate-opening behavior.

Mesoscopic architectures of porous coordination polymers fabricated by pseudomorphic replication.

The spatial organization of porous coordination polymer (PCP) crystals into higher-order structures is critical for their integration into separation systems, heterogeneous catalysts, ion/electron transport and photonic devices. Here, we demonstrate a rapid method to spatially control the nucleation site, leading to the formation of mesoscopic architecture made of PCPs, in both two and three dimensions. Inspired by geological processes, this method relies on the morphological replacement of a shaped sacrificial metal oxide used both as a metal source and as an 'architecture-directing agent' by an analogous PCP architecture. Spatiotemporal harmonization of the metal oxide dissolution and the PCP crystallization allowed the preservation of very fine mineral morphological details of periodic alumina inverse opal structures. The replication of randomly structured alumina aerogels resulted in a PCP architecture with hierarchical porosity in which the hydrophobic micropores of the PCP and the mesopores/macropores inherited from the parent aerogels synergistically enhanced the material's selectivity and mass transfer for water/ethanol separation.

Precise control and consecutive modulation of spin transition temperature using chemical migration in porous coordination polymers.

Precise control of spin transition temperature (T(c)) is one of the most important challenges in molecular magnetism. A Hofmann-type porous coordination polymer {Fe(pz)[Pt(II)(CN)(4)]} (1; pz = pyrazine) exhibited cooperative spin transition near room temperature (T(c)(up) = 304 K and T(c)(down) = 284 K) and its iodine adduct {Fe(pz)[Pt(II/IV)(CN)(4)(I)]} (1-I), prepared by oxidative addition of iodine to the open metal sites of Pt(II), raised the T(c) by 100 K. DSC and microscopic Raman spectra of a solid mixture of 1-I and 1 revealed that iodine migrated from 1-I to 1 through the grain boundary after heating above 398 K. We have succeeded in precisely controlling the iodine content of {Fe(pz)[Pt(CN)(4)(I)(n)]} (1-In; n = 0.0-1.0), which resulted in consecutive modulation of T(c) in the range 300-400 K while maintaining the hysteresis width. Furthermore, it was demonstrated that iodine migration in the solid mixture was triggered by the spin transition of 1-I. The magnetically bistable porous framework decorating guest interactive open-metal-site in the pore surface makes it possible to modulate T(c) ad arbitrium through unique postsynthetic method using iodine migration.