Purely Physisorption‐Based CO‐Selective Gate‐Opening in Microporous Organically Pillared Layered Silicates

Herling, Markus M.; Rieß, Martin; Satō, Hiroshi; Li, Liangchun; Martin, Thomas; Kalo, Hussein; Matsuda, Ryotaro; Kitagawa, Susumu; Breu, Josef

doi:10.1002/anie.201710717

Cited by 7 publications

(3 citation statements)

References 60 publications

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“…Instead, coadsorption studies would be needed as the pore-opening gas could also allow a second gas to be adsorbed together. We note, however, that in the literature the selectivity estimate in flexible networks appears typically to be based on the uptakes of the single-gas components. ,,− A material with selective moisture uptake could be very interesting for the humidity control since the working capacity of the desiccant should not be affected by other components of air.…”

Section: Resultsmentioning

confidence: 99%

Water Vapor Single-Gas Selectivity via Flexibility of Three Potential Materials for Autonomous Indoor Humidity Control

Tsobnang

Hastürk

Fröhlich

et al. 2019

Crystal Growth & Design

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Two new isostructural porous supramolecular materials {[Cu 2 (amp) 4 Cl][M(C 2 O 4 ) 3 ]•6H 2 O} n (amp = 2-aminomethylpyridine), designated as II and III for M = Cr(III) and M = Fe(III) respectively, have been synthesized by a self-assembly process of two ionic complexes [Cu 2 (amp) 4 Cl] 3+ and [M(C 2 O 4 ) 3 ] 3− , M = Fe(III) and Cr(III). They build heterometallic hydrogenbonded-, oxalato-and chlorido-bridged zigzag chains with interchain hydrogen bonds and π−π interactions. This results in supramolecular potentially porous architectures exhibiting large channels filled with hexameric water clusters. Their activated phases, II′ and III′, can readsorb the water molecules to regenerate the initial materials which are stable for many water adsorption and desorption cycles like that of their homologous catena-{ [(Co(amp) 3 ][Cr(C 2 O 4 ) 3 ]•6H 2 O} (I′). The three materials I′, II′, and III′ exhibit water adsorption and desorption isotherms having a sigmoidal shape and resulting in the combination of a type I(b) profile followed by an S-shaped type V isotherm with hysteresis. At 20 °C, the steep water sorption of the S-shaped isotherm occurs at 0.1P/P 0 for II′ and III′. This water sorption behavior is quite different from the related compound I′, where a gate opening and closure process is involved, giving a type V isotherm with a pronounced H1-type hysteresis loop with parallel and steep adsorption (at 0.25P/P 0 ) and desorption branches (at 0.17P/P 0 ). The water adsorption capacities of the three materials I′, II′, and III′ are 17, 12, and 11 wt %, respectively. Temperature does not have a great effect on their water sorption properties, and they all exclude N 2 and CO 2 gases in the low pressure range. Compounds II′ and III′ are classified among the materials for which the dehumidification and the humidification trigger points are the same or too close (10% relative humidity (r.H.) in their case), while I′ shows a good potential to be used for automatic indoor control in the range of 15−25% r.H. recommended for many activities. All the differences observed in the water sorption properties of the three materials are related to (i) the type of water cluster which is built in each material, (ii) the strength of the hydrogen bonds within each water cluster and between the clusters and its host, and (iii) the strength of the intrahost interactions which keep the pores of the material closed.

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Section: Resultsmentioning

confidence: 99%

Water Vapor Single-Gas Selectivity via Flexibility of Three Potential Materials for Autonomous Indoor Humidity Control

Tsobnang

Hastürk

Fröhlich

et al. 2019

Crystal Growth & Design

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“…[41].Copyright( 2016)American ChemicalS ociety. ; c and d: [42] Chem.E ur.J. 2019, 25,2103 -2111 www.chemeurj.org Concept other industrially relevant gas mixtures.I na ddition, pillars with cooperative bonding functionalities could be applied to improve selectivity.…”

Section: Discussionmentioning

confidence: 99%

“…This gate‐opening of MOPS‐5 is reversible and furthermore selective for CO over N 2 . Once again, the selective nature of the gate‐opening is most likely correlated with the different multipole moments of CO and N 2 rather than with the marginal size differences (kinetic diameter 3.76 and 3.64 Å for CO and N 2 , respectively) . Competitive co‐adsorption experiments to determine reliable separation coefficients are already in progress.…”

Section: A Meticulous Electrostatic Balance Controls the Type Of Gatementioning

confidence: 99%

Microporous Organically Pillared Layered Silicates (MOPS): A Versatile Class of Functional Porous Materials

Rieß

Senker

Schobert

et al. 2018

Chemistry A European J

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The design of microporous hybrid materials, tailored for diverse applications, is a key to address our modern society's imperative of sustainable technologies. Prerequisites are flexible customization of host-guest interactions by incorporating various types of functionality and by adjusting the pore structure. On that score, metal-organic frameworks (MOFs) have been the reference in the past decades. More recently, a new class of microporous hybrid materials emerged, microporous organically pillared layered silicates (MOPS). MOPS are synthesized by simple ion exchange of organic or metal complex cations in synthetic layered silicates. MOFs and MOPSs share the features of "component modularity" and "functional porosity". While both, MOFs and MOPS maintain the intrinsic characteristics of their building blocks, new distinctive properties arise from their assemblage. MOPS are unique since allowing for simultaneous and continuous tuning of micropores in the sub-Ångström range. Consequently, with MOPS the adsorbent recognition may be optimized without the need to explore different framework topologies. Similar to the third generation of MOFs (also termed soft porous crystals), MOPS are structurally ordered, permanently microporous solids that may also show a reversible structural flexibility above a distinct threshold pressure of certain adsorbents. This structural dynamism of MOPS can be utilized by meticulously adjusting the charge density of the silicate layers to the polarizability of the adsorbent leading to different gate opening mechanisms. The potential of MOPS is far from being fully explored. This Concept article highlights the main features of MOPS and illustrates promising directions for further research.

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Giant Multistep Crystalline vs. Osmotic Swelling of Synthetic Hectorite in Aqueous Acetonitrile

Kunz

Amschler

Edenharter

et al. 2019

Clays and clay miner.

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Intercalation of large organocations into 2:1 clay minerals may be hampered by two problems: on one hand, the solubility of organocations in water is limited and the resulting high selectivity for adsorption in the polar solvent may lead to non-equilibrium structures. On the other hand, the large expansion of the interlayer space will slow down kinetics of ion exchange considerably. The best workaround for these obstacles is to suspend the clay minerals in mixtures of water with more hydrophobic organic solvents that nevertheless trigger a considerable expansion of the interlayer space by swelling. This in turn fosters ion exchange. The current study, therefore, revisited pioneering work by Bradley (1945) and investigated the swelling behavior of synthetic sodium hectorite (Na-hec) as a function of the composition of the swelling solvent, a mixture of acetonitrile and water. Up to a maximum acetonitrile content of 65 vol.%, delamination by osmotic swelling occurred. At even higher acetonitrile concentrations, swelling was limited to the crystalline swelling regime where a step-like adjustment of the d value was observed. Several mixtures were identified yielding a well defined and uniform interlayer height as evidenced by rational 00l-series with the d spacing decreasing with increasing acetonitrile content. Surprisingly, for a specific acetonitrile:water ratio even an ordered interstratification of two strictly alternating interlayer heights with distinctly different solvent compositions was observed.

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Purely Physisorption‐Based CO‐Selective Gate‐Opening in Microporous Organically Pillared Layered Silicates

Cited by 7 publications

References 60 publications

Water Vapor Single-Gas Selectivity via Flexibility of Three Potential Materials for Autonomous Indoor Humidity Control

Water Vapor Single-Gas Selectivity via Flexibility of Three Potential Materials for Autonomous Indoor Humidity Control

Microporous Organically Pillared Layered Silicates (MOPS): A Versatile Class of Functional Porous Materials

Giant Multistep Crystalline vs. Osmotic Swelling of Synthetic Hectorite in Aqueous Acetonitrile

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