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A flexible bipyridinium ligand has been introduced into a series of isomorphous metal-organic frameworks to yield porous materials with subtriangular 1D channel and cagelike pore space. The introduction of bipyridinium molecules into the porous frameworks leads to the formation of 1D channel with positively charged surface, which shows high affinities to polar molecules such as methanol, ethanol, and water vapor. Additionally, the bipyridinium molecules possess conjugated pyridyl rings connected by carbon-carbon single bonds, which can rotate freely to keep twisted or large-conjugated planar configuration by controlling coordination condition during the self-assembly process. The cagelike pore space formed by these flexible bipyridinium molecules contains arene-arene stacked pyridyl rings and thus renders abundant π-π interaction sites for efficient adsorption of benzene and toluene molecules, and is also large enough to accommodate cyclohexane molecules. These metal-organic frameworks show efficient adsorption for benzene, toluene, and cyclohexane molecules through high utilization efficiency of unique pore space, and display rarely broad-spectrum adsorptivity to various organic pollutants with hydrophilic/hydrophobic, conjugated/nonconjugated characteristics. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) are promising nanomaterials with unprecedented capacity to store small molecules. Despite this huge capacity, proposed methods for releasing these molecules are not yet feasible at a meaningful scale, largely because of the strong binding of the molecules and the thermally insulating nature of the adsorbent. It is likely that large amounts of energy would be required for operation at scale. Furthermore, the high adsorption capacity of MOFs is not typically matched by a high working capacity; adsorbed molecules are not readily retrieved. Here we show a series of magnetic framework composites (MFCs) synthesized from ferri-magnetic MgFe2O4 nanoparticles and the Zr-based MOF UiO-66 can be deployed in a magnetic induction swing adsorption process for CO2 capture and release. Exposure of the MFCs to an alternating current magnetic field resulted in the generation of heat by the embedded magnetic nanoparticle and fast release of CO2 from the MOF, with an unprecedented 100% of adsorbed CO2 released under a 42 mT field. This was achieved at a regeneration time of 240 s. The efficiency of the MISA process was shown to be dependent on the amount of MFC used, with efficiencies reaching 60% at just a gram scale. These local "nanoheaters" overcome the thermally insulating nature of the adsorbent, which has promising implications for use at scale. Additionally, the ability to access 100% of the adsorption capacity permits the use of strongly adsorbing, high-capacity MOFs that were previously discarded. [ABSTRACT FROM AUTHOR]

The adsorption mechanism of ethane, ethylene, and acetylene (C2Hn; n = 2, 4, 6) on two microporous metal organic frameworks (MOFs) is described here that is consistent with observations from single crystal and powder X-ray diffraction, calorimetric measurements, and gas adsorption isotherm measurements. Two calcium-based MOFs, designated as SBMOF-1 and SBMOF-2 (SB: Stony Brook), form three-dimensional frameworks with one-dimensional open channels. As determined from single crystal diffraction experiments, channel geometries of both SBMOF-1 and SBMOF-2 provide multiple adsorption sites for hydrocarbon molecules through C-H···π and C-H···O interactions, similarly to interactions in the molecular and protein crystals. Both materials selectively adsorb C2 hydrocarbon gases over methane as determined with IAST and breakthrough calculations as well as experimental breakthrough measurements, with C2H6/CH4 selectivity as high as 74 in SBMOF-1. [ABSTRACT FROM AUTHOR]

Twoisomorphous lanthanide–organic frameworks, Ln(BDC)1.5(DMF)(H2O) (Ln = Er (1), Tm (2)) have been synthesized based on 1,4-benzenedicarboxylicacid (H2BDC). Because of the 2-fold interpenetration, thepores are partly blocked and there are no significant gas adsorptionsfor these two interpenetrating nets. Through control over interpenetrationby applying an organic ligand with hindrance groups or replacing coordinatedsolvent molecules with a chelating ligand, three non-interpenetratinglanthanide–organic frameworks, Er2(BDC)3(phen)2·3H2O (3), Tm(TBDC)1.5(DMF)(H2O)·2H2O (4), Er2(TBDC)3(phen)2·4DMF·2H2O (5), possessing the same topology with 1and 2, have been synthesized and characterized.Further changing reaction conditions, three other porous lanthanide–organicframeworks with different structures with 1–5, Tm(BDC)1.5(H2O)·0.5DMF·C2H5OH·2H2O (6), Tm4(BDC)6(H2O)2(DMF)(C2H5OH)·2DMF·2H2O (7),and Sm(TBDC)1.5(phen)(H2O)·DMF·H2O (8), have been constructed. Gas sorption measurementsfor 5, 6, 7, and 8have been carried out and revealed that these materials possesspermanent porosity. The catalytic property for complex 6has also been studied. [ABSTRACT FROM AUTHOR]

Porous NOTT-202a shows exceptionally high uptake of SO2, 13.6 mmol g-1 (87.0 wt %) at 268 K and 1.0 bar, representing the highest value reported to date for a framework material. NOTT-202a undergoes a distinct irreversible framework phase transition upon SO2 uptake at 268-283 K to give NOTT-202b which has enhanced stability due to the formation of strong π···π interactions between interpenetrated networks. [ABSTRACT FROM AUTHOR]

As a class of porous materials, metal–organicframeworks(MOFs) show promise for the adsorption-based separation of mixturesof gases. The design of any process involving selective adsorptionrequires knowledge of mixture adsorption isotherms. Ideal adsorbedsolution theory (IAST) predicts mixture adsorption equilibria usingonly single-component data, thereby minimizing the need for experimentaladsorption data. In this work we perform a systematic study of theapplicability of IAST to MOFs by using grand canonical Monte Carlo(GCMC) simulations to investigate the suitability of IAST for theprediction of the adsorption of mixtures of molecules of differingsizes, asphericities, and polarities in a range of structurally differentMOFs. We show that IAST is generally accurate for MOFs. Where we findIAST is less accurate, deviations result from both mixture effects,in the form of nonidealities in the adsorbed phase, and characteristicsof the adsorbent structures. In terms of the MOF structure, departuresfrom IAST are a consequence of heterogeneities both on the scale ofthe unit cell and on shorter length scales, whereby competition foradsorption sites has a strong influence. [ABSTRACT FROM AUTHOR]