Search

Guest transport through discrete voids (closed pores) in crystalline solids is poorly understood. Herein, we report the gas sorption properties of a nonporous coordination network, [Co(bib)2Cl2]n·2MeOH (sql-bib-Co-Cl-α), featuring square lattice (sql) topology and the bent linker 1,3-bis(1H-imidazol-1-yl)benzene (bib). The as-synthesized sql-bib-Co-Cl-α has 11.3% (313 Å3) of its unit cell volume in closed pores occupied by methanol (MeOH). Upon desolvation and air exposure, sql-bib-Co-Cl-α underwent a single-crystal to single-crystal (SC-SC) phase transformation to sql-bib-Co-Cl-β', wherein MeOH was replaced by water. Activation (vacuum or N2 flow) resulted in dehydration and retention of the closed pores, affording sql-bib-Co-Cl-β with 7.7% (194 Å3) guest-accessible space. sql-bib-Co-Cl-β was found to preferentially adsorb C2H2 (at 265 K) over CO2 (at 195 K) through gate-opening mechanisms, at gate-opening pressures of 31.1 and 59.8 kPa, respectively, while other C2 gases were excluded. PXRD was used to monitor transformations between the three phases of sql-bib-Co-Cl, while in situ DSC, in situ SCXRD under CO2 pressure, and computational studies provided insight into the guest transport mechanism, which we attribute to the angular, flexible nature of the bib ligand. Further the preferential adsorption of C2H2 over CO2 and other C2 gases suggests that transiently porous sorbents might have utility in separations., (© 2025 Wiley‐VCH GmbH.)

Griseofulvin represents a rare case of a close-packed organic apohost that can clathrate selected volatile guests in a solid-gas fashion. Inclusion mechanisms and solvent exchange were investigated by a combination of single crystal and powder X-ray diffraction, coupled to optical microscopy and thermal analyses. In particular, gas diffusion and dissolution/recrystallization are alternatively observed, depending on the host polymorph, as well as the chemical nature of the guest and its physical state., (© 2024 The Author(s). Chemistry - A European Journal published by Wiley-VCH GmbH.)

Herein, we report that a new flexible coordination network, NiL 2 (L=4-(4-pyridyl)-biphenyl-4-carboxylic acid), with diamondoid topology switches between non-porous (closed) and several porous (open) phases at specific CO 2 and CH 4 pressures. These phases are manifested by multi-step low-pressure isotherms for CO 2 or a single-step high-pressure isotherm for CH 4 . The potential methane working capacity of NiL 2 approaches that of compressed natural gas but at much lower pressures. The guest-induced phase transitions of NiL 2 were studied by single-crystal XRD, in situ variable pressure powder XRD, synchrotron powder XRD, pressure-gradient differential scanning calorimetry (P-DSC), and molecular modeling. The detailed structural information provides insight into the extreme flexibility of NiL 2 . Specifically, the extended linker ligand, L, undergoes ligand contortion and interactions between interpenetrated networks or sorbate-sorbent interactions enable the observed switching., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Sequestration of CO2, either from gas mixtures or directly from air (direct air capture, DAC), could mitigate carbon emissions. Here five materials are investigated for their ability to adsorb CO2 directly from air and other gas mixtures. The sorbents studied are benchmark materials that encompass four types of porous material, one chemisorbent, TEPA-SBA-15 (amine-modified mesoporous silica) and four physisorbents: Zeolite 13X (inorganic); HKUST-1 and Mg-MOF-74/Mg-dobdc (metal-organic frameworks, MOFs); SIFSIX-3-Ni, (hybrid ultramicroporous material). Temperature-programmed desorption (TPD) experiments afforded information about the contents of each sorbent under equilibrium conditions and their ease of recycling. Accelerated stability tests addressed projected shelf-life of the five sorbents. The four physisorbents were found to be capable of carbon capture from CO2-rich gas mixtures, but competition and reaction with atmospheric moisture significantly reduced their DAC performance., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Non-stoichiometric molecular mixed crystals have potential as functional materials, the properties of which can be tailored by rationally changing their composition. The guidelines for their preparation were summarized over thirty years ago by Alexander Kitaigorodsky. Here those principles are revised in light of new studies on the acridine/phenazine system, and solvent-assisted grinding is presented as a convenient synthetic procedure to afford a more homogeneous product than traditional solvent-evaporation methods. Finally, the proposed prerequisite of crystal isostructurality/isomorphicity for the pure compounds, which seems to be violated in the present case, is discussed., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A topological triptych: Three molecular links, a [2]catenane, a trefoil knot, and a Solomon link, were obtained in one pot through the self-assembly of two simple ligands in the presence of Zn(II). The approach relied on dynamic covalent chemistry and metal templation., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A Werner complex is highly selective for o-xylene in a vapor mixture containing all three isomers. However, in the absence of o-xylene, the substrate shows similar selectivity for m-xylene over p-xylene. Kinetic studies show a different trend whereby m-xylene is absorbed most rapidly, implying that thermodynamic factors must be responsible for the selectivity., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

18-Crown[6] ether has been used to prepare a new class of organic-inorganic complexes of general formula 18-crown[6]M[HSO(4)](n) (where M = NH(4) (+), K(+), Sr(2+) and n = 1, 2) by reacting directly in solution or in the solid state the crown ether 18-crown[6] with inorganic salts such as [NH(4)][HSO(4)], K[HSO(4)], and Sr[HSO(4)](2). The structures of 18-crown[6][NH(4)][HSO(4)]2 H(2)O (12 H(2)O), 18-crown[6][NH(4)][HSO(4)] (1), 18-crown[6]K[HSO(4)]2 H(2)O (22 H(2)O), 18-crown[6]K[HSO(4)] (2), and 18-crown[6]Sr[HSO(4)](2) (3) have been characterized by single-crystal X-ray diffraction. The reversible water loss in compounds 12 H(2)O and 22 H(2)O leads to formation of the corresponding anhydrous phases 18-crown[6][NH(4)][HSO(4)] (1), and 18-crown[6]K[HSO(4)] (2), which undergo, on further heating, enantiotropic solid-solid transitions very likely associated with the on-set of a solid state dynamical process. Similar high-temperature behavior is shown by 18-crown[6]Sr[HSO(4)](2) (3). The dehydration and phase-transition processes have been investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and variable temperature X-ray powder diffraction.