Solid-vapor sorption of xylenes: Prioritized selectivity as a means of separating all three isomers using a single substrate

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.</p

Solid–vapour reactions as a post-synthetic modification tool for molecular crystals: The enclathration of benzene and toluene by Werner complexes

The enclathration of benzene and toluene by Werner complexes has been described. In the case of toluene, time-lapse PXRD analysis reveals that solid–liquid and solid–vapour reactions proceed according to different pathways. These preliminary results suggest that solid–liquid reactions destroy the host structure, whereas the solid–vapour reactions allow post-synthetic modification. © 2013 The Royal Society of Chemistry.</p

Determining hydrogen atom positions for hydrogen bonded interactions: A distance-dependent neutron-normalized method

Crystal structures determined by neutron and X-ray diffraction were retrieved from the Cambridge Structural Database (CSD), and hydrogen-bond geometrical descriptors (distances and angles) have been pairwisely compared, confirming that the two techniques produce significantly different results for the determination of hydrogen atom positions. Inclusion of neutron-normalized data shows that normalization fails to correct for bond polarization when applied to H-bond interactions. Statistical analysis has been carried out, and an empirical method is suggested for calculating more accurate positions for the hydrogen atoms involved in hydrogen bond formation. The simplicity of the approach is promising for future implementation in common crystal structure analysis software packages. The results are presented with a view to opening a discussion on how to approach one of the main limitations of X-ray diffraction in the area of structural chemistry. © 2011 American Chemical Society.</p

Temperature-dependent guest reorientation: A reversible order-disorder transformation in a single crystal

A Werner clathrate undergoes a reversible, temperature-induced, single-crystal to single-crystal polymorphic transformation. Such transformation involves a realignment of the Werner complex, which generates a twofold axis and increases the space group symmetry from P21/n to C2/c. An increase of the crystal's dynamic disorder is also associated with the phase transition. Crystallographic and thermal behaviours are discussed. © 2014 The Royal Society of Chemistry.</p

Isostructural coordination polymers: Epitaxis vs. solid solution

Different synthetic conditions often afford different products and this is more evident for complex structures (i.e. solvates, polymorphs, co-crystals, solid solutions, etc.). We show how solution growth of a given set of components produces an epitaxial heterocrystal while mechanochemical synthesis yields a solid solution. © 2011 The Royal Society of Chemistry.</p

A mechanochemically synthesised solid solution enables engineering of the sorption properties of a Werner clathrate

Mechanochemical synthesis has been used to obtain two Werner complexes and their solid solution that could not be obtained by conventional “wet” chemistry; remarkably, despite the structural and chemical similarity, the solid solution exhibits sorption properties that differ from those of the pure compounds. © 2012 Royal Society of Chemistry.</p

A Needle in a Haystack: Transient Porosity in a Closed Pore Square Lattice Coordination Network

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] ⋅ 2MeOH}n (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 59.8 and 27.7 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 The Author(s). Angewandte Chemie International Edition published by Wiley-VCH GmbH.</p

Reversible Switching between Highly Porous and Nonporous Phases of an Interpenetrated Diamondoid Coordination Network That Exhibits Gate-Opening at Methane Storage Pressures

Herein, we report that a new flexible coordination network, NiL2 (L=4-(4-pyridyl)-biphenyl-4-carboxylic acid), with diamondoid topology switches between non-porous (closed) and several porous (open) phases at specific CO2 and CH4 pressures. These phases are manifested by multi-step low-pressure isotherms for CO2 or a single-step high-pressure isotherm for CH4. The potential methane working capacity of NiL2 approaches that of compressed natural gas but at much lower pressures. The guest-induced phase transitions of NiL2 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 NiL2. 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</p