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Abstract: Coagulation factor XII (FXII) is a key initiator of the contact pathway, which contributes to inflammatory pathways. FXII circulates as a zymogen, which when auto-activated forms factor XIIa (FXIIa). Here, the production of the recombinant FXIIa protease domain (βFXIIaHis) with yields of ∼1–2 mg per litre of insect-cell culture is reported. A second construct utilized an N-terminal maltose-binding protein (MBP) fusion (MBP-βFXIIaHis). Crystal structures were determined of MBP-βFXIIaHis in complex with the inhibitor D-Phe-Pro-Arg chloromethyl ketone (PPACK) and of βFXIIaHis in isolation. The βFXIIaHis structure revealed that the S2 and S1 pockets were occupied by Thr and Arg residues, respectively, from an adjacent molecule in the crystal. The Thr-Arg sequence mimics the P2–P1 FXIIa cleavage-site residues present in the natural substrates prekallikrein and FXII, and Pro-Arg (from PPACK) mimics the factor XI cleavage site. A comparison of the βFXIIaHis structure with the available crystal structure of the zymogen-like FXII protease revealed large conformational changes centred around the S1 pocket and an alternate conformation for the 99-loop, Tyr99 and the S2 pocket. Further comparison with activated protease structures of factors IXa and Xa, which also have the Tyr99 residue, reveals that a more open form of the S2 pocket only occurs in the presence of a substrate mimetic. The FXIIa inhibitors EcTI and infestin-4 have Pro-Arg and Phe-Arg P2–P1 sequences, respectively, and the interactions that these inhibitors make with βFXIIa are also described. These structural studies of βFXIIa provide insight into substrate and inhibitor recognition and establish a scaffold for the structure-guided drug design of novel antithrombotic and anti-inflammatory agents.

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Abstract: The development of materials that are non-magnetic in the bulk but exhibit two-dimensional (2D) magnetism at the surface is at the core of spintronics applications. Here, we present the valence-fluctuating material EuIr2Si2, where in contrast to its non-magnetic bulk, the Si-terminated surface reveals controllable 2D ferromagnetism. Close to the surface the Eu ions prefer a magnetic divalent configuration and their large 4f moments order below 48 K. The emerging exchange interaction modifies the spin polarization of the 2D surface electrons originally induced by the strong Rashba effect. The temperature-dependent mixed valence of the bulk allows to tune the energy and momentum size of the projected band gaps to which the 2D electrons are confined. This gives an additional degree of freedom to handle spin-polarized electrons at the surface. Our findings disclose valence-fluctuating rare-earth based materials as a very promising basis for the development of systems with controllable 2D magnetic properties which is of interest both for fundamental science and applications.

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Abstract: Current methods for the extraction of rhodium carry the highest carbon footprint and worst pollution metrics of all of the elements used in modern technological applications. Improving upon existing methods is made difficult by the limited understanding of the molecular-level chemistry occurring in extraction processes, particularly in the hydrometallurgical separation step. While many of the precious metals can be separated by solvent extraction, there currently exist no commercial extractants for Rh. This is due to its complicated mixed speciation upon leaching into hydrochloric acid, which gives rise to difficulties in designing effective reagents for solvent extraction. Herein we show that the diamidoamine reagent N-n-hexylbis(N-methyl-N-n-octylethylamide)amine transports Rh(III) from aqueous HCl into an organic phase as the monoaquated dianion [RhCl5(H2O)]2– through the formation of an outer-sphere assembly; this assembly has been characterized by experimentation (slope analysis, FT-IR and NMR spectroscopy, EXAFS, SANS, and ESI-MS) and computational modeling. The paper demonstrates the importance of applying a broad range of techniques to obtain a convincing mode of action for the complex processes involved in anion recognition in the solution phase. A consistent and comprehensive understanding of how the ligand operates to achieve Rh(III) selectivity over the competitor anion Cl– has emerged. This knowledge will guide the design of extractants and thus offers promise for improving the sustainability of metal extraction from both traditional mining sources and the recycling of secondary source materials.

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Abstract: In this contribution, we introduce a simple approach to quickly estimate the environment-induced crack velocity (CV) as a function of the calculated applied stress intensity factor (K) developed during the slow strain rate testing of aluminum alloys exposed to aqueous or humid air-type environments. The CV-K behavior for a commercial aluminum-magnesium alloy, AA5083-H131, sensitized and pre-exposed to a 0.6 m NaCl solution has been estimated from slow strain rate test data. The predicted threshold K and crack velocities match recently published data for the same alloy in similarly sensitized conditions where the CV-K data were obtained using state-of-the-art fracture mechanics-based testing.

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Abstract: Supramolecular Coordination Compounds (SCCs) represent the power of Coordination Chemistry methodologies to self-assemble discrete architectures with targeted properties. SCCs are generally synthesised in solution, with isolat-ed fully-coordinated metal atoms as structural nodes, thus severely limited as metal-based catalysts. Metal-Organic Frameworks (MOFs) show unique features to act as chemical nanoreactors for the in-situ synthesis and stabilization of otherwise not accessible functional species. Here, we present the self-assembly of PdII SCCs within the confined space of a preformed MOF (SCCs@MOF) and its post-assembly metalation to give a PdII-AuIII supramolecular assembly, crys-tallography underpinned. These SCCs@MOF catalyse the coupling of boronic acids and/or alkynes, representative multisite metallic-catalysed reactions in which traditional SCCs tend to decompose, and retain its structural integrity as consequence of the synergetic hybridization between SCCs and MOF. These results open new avenues in both the synthesis of novel SCCs and their use on heterogeneous metal-based Supramolecular Catalysis.