Research Articles (Chemistry and Polymer Science)

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    Breaking the trade-off between selectivity and adsorption capacity for gas separation
    (Elsevier Inc., 2021-11) Soumya, Naveen Kumar; Mukherjee, Nathan C.; Bezrukov, Andrey A.; Tan, Kui; Martins, Vinicius; Vandichel, Matthias; Pham, Tony; Van Wyk, Lisa M.; Oyekan, Kolade; Kumar, Amrit; Forrest, Katherine A.; Patil, Komal M.; Barbour, Leonard J.; Space, Brian; Huang, Yining; Kruger, Paul E.; Zaworotko, Michael J.
    The trade-off between selectivity and adsorption capacity with porous materials is a major roadblock to reducing the energy footprint of gas separation technologies. To address this matter, we report herein a systematic crystal engineering study of C2H2 removal from CO2 in a family of hybrid ultramicroporous materials (HUMs). The HUMs are composed of the same organic linker ligand, 4-(3,5-dimethyl-1H-pyrazol-4-yl)pyridine, pypz, three inorganic pillar ligands, and two metal cations, thereby affording six isostructural pcu topology HUMs. All six HUMs exhibited strong binding sites for C2H2 and weaker affinity for CO2. The tuning of pore size and chemistry enabled by crystal engineering resulted in benchmark C2H2/CO2 separation performance. Fixed-bed dynamic column breakthrough experiments for an equimolar (v/v = 1:1) C2H2/CO2 binary gas mixture revealed that one sorbent, SIFSIX-21-Ni, was the first C2H2 selective sorbent that combines exceptional separation selectivity (27.7) with high adsorption capacity (4 mmol·g−1).
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    Facile synthesis of a C4-symmetrical inherently chiral calix[4]arene†
    (Royal Society of Chemistry, 2021-09) Hodson, Luke; Visagie, Kevin J.; Smith, Michael-Phillip; Loots, Leigh; Kuter, David; Snayer, Tregen M.
    Inherently chiral calix[4]arenes with C4-symmetry are extremely rare and difficult to synthesise, severely hampering any effort to expand on their potential as chiral supramolecular catalysts and building blocks. Herein we report a reaction of a tetracarbamate calix[4]arene with NBS which results in a high yield of an inherently chiral calix[4]arenes with C4-symmetry. Furthermore, employing a chiral N-Boc proline moiety allows for separation of the diastereomers formed, thus obtaining the pure enantiomers after hydrolysis. The enantiomers could be assigned based on the CD spectra and DFT calculated values.
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    Tuning extreme anisotropic thermal expansion in 1D coordination polymers through metal selection and solid solutions†
    (Royal Society of Chemistry, 2021-07) Van Wyk, Lisa M.; Loots, Leigh; Barbour, Leonard J.
    The thermal expansion behaviour of a series of 1D coordination polymers has been investigated. Variation of the metal centre allows tuning of the thermal expansion behaviour from colossal positive volumetric to extreme anomalous thermal expansion. Preparation of solid solutions increased the magnitude of the anomalous thermal expansion further, producing two species displaying supercolossal anisotropic thermal expansion (ZnCoCPHTαY2 = −712 MK−1, αY3 = 1632 MK−1 and ZnCdCPHTαY2 = −711 MK−1, αY3 = 1216 MK−1).
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    A comprehensive analysis in one run – in-depth conformation studies of protein–polymer chimeras by asymmetrical flow field-flow fractionation †
    (Royal Society of Chemistry, 2021-09) Kaupbayeva, Bibifatima; Murata, Hironobu; Matyjaszewski, Krzysztof; Russell, Alan J.; Boye, Susanne; Lederer, Albena
    Polymer-based protein engineering has enabled the synthesis of a variety of protein–polymer conjugates that are widely applicable in therapeutic, diagnostic and biotechnological industries. Accurate characterizations of physical–chemical properties, in particular, molar masses, sizes, composition and their dispersities are critical parameters that determine the functionality and conformation of protein–polymer conjugates and are important for creating reproducible manufacturing processes. Most of the current characterization techniques suffer from fundamental limitations and do not provide an accurate understanding of a sample's true nature. In this paper, we demonstrate the advantage of asymmetrical flow field-flow fractionation (AF4) coupled with multiple detectors for the characterization of a library of complex, zwitterionic and neutral protein–polymer conjugates. This method allows for determination of intrinsic physical properties of protein–polymer chimeras from a single, rapid measurement.
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    Mechanically compliant single crystals of a stable organic radical†
    (Royal Society of Chemistry, 2021-03) Commins, Patrick; Dippenaar, A. Bernard; Li, Liang; Hara, Hideyuki; Haynes, Delia A.; Naumov, Pance
    Mechanically compliant organic crystals are the foundation of the development of future flexible, light-weight single-crystal electronics, and this requires reversibly deformable crystalline organic materials with permanent magnetism. Here, we report and characterize the first instance of a plastically bendable single crystal of a permanent organic radical, 4-(4′-cyano-2′,3′,4′,5′-tetrafluorophenyl)-1,2,3,5-dithiadiazolyl. The weak interactions between the radicals render single crystals of the β phase of this material exceedingly soft, and the S–N interactions facilitate plastic bending. EPR imaging of a bent single crystal reveals the effect of deformation on the three-dimensional spin density of the crystal. The unusual mechanical compliance of this material opens prospects for exploration into flexible crystals of other stable organic radicals towards the development of flexible light-weight organic magnetoresistance devices based on weak, non-hydrogen-bonded interactions in molecular crystals.