A hydrophobic CO 2 physisorbent Most materials for carbon dioxide (CO 2 ) capture of fossil fuel combustion, such as amines, rely on strong chemisorption interactions that are highly selective but can incur a large energy penalty to release CO 2 . Lin et al . show that a zinc-based metal organic framework material can physisorb CO 2 and incurs a lower regeneration penalty. Its binding site at the center of the pores precludes the formation of hydrogen-bonding networks between water molecules. This durable material can preferentially adsorb CO2 at 40% relative humidity and maintains its performance under flue gas conditions of 150°C. —PDS

A new phosphonate metal-organic framework (MOF) with a layered motif but not that of the classical hybrid inorganic-organic solid is presented. Zn, henceforth denoted as PCMOF-3, contains a polar interlayer lined with Zn-ligated water molecules and phosphonate oxygen atoms. These groups serve to anchor free water molecules into ordered chains, as observed by X-ray crystallography. The potential for proton conduction via the well-defined interlayer was studied by 2 H solid-state NMR spectroscopy and AC impedance spectroscopy. The proton conductivity in H 2 was measured as 3.5 × 10 -5 S cm -1 at 25 °C and 98% relative humidity. More interestingly, an Arrhenius plot gave a low activation energy of 0.17 eV for proton transfer, corroborating the solid-state NMR data that showed exchange between all deuterium sites in the D 2 O analogue of PCMOF-3, even at -20 °C.

A crystalline and permanently porous copper phosphonate monoester framework has been synthesized from a tetraaryl trigonal phosphonate monoester linker. This material has a surface area over 1000 m g , as measured by N sorption, the highest reported for a phosphonate-based metal-organic framework (MOF). The monoesters result in hydrophobic pore surfaces that give a low heat of adsorption for CO and low calculated selectivity for CO over N and CH in binary mixtures. By careful manipulation of synthetic conditions, it is possible to selectively remove some of the monoesters lining the pore to form a hydrogen phosphonate while giving an isomorphous structure. This increases the affinity of the framework for CO giving higher ambient uptake, higher heat of adsorption, and much higher calculated selectivity for CO over both N and CH . Formation of the acid groups is noteworthy as complexation with the parent acid gives a different structure.

Metal organic frameworks (MOFs) are noted for crystallinity, stability, and porosity. For many industrial challenges though, beyond stability to pore activation, porous materials require high thermal and moisture stability. Here, we report a Sn(IV) triphosphonate framework, CALF-28, that is highly robust and porous. CALF-28 was designed based on the known structure of a divalent metal phosphonate that was 2-fold interpenetrated. It has strong sustaining interactions but consequently rapidly precipitates, compromising crystallinity. Using methods to enhance order, and by analogy to the M(II) analogue, insights to the structure are ascertained and corroborated by PXRD and gas sorption analysis. CALF-28 has a surface area >500 m(2)/g and is stable in water.