Materials that display multiple stepped spin crossover (SCO) transitions with accompanying hysteresis present the opportunity for ternary, quaternary, and quinary electronic switching and data ...storage but are rare in existence. Herein, we present the first report of a four‐step hysteretic SCO framework. Single‐crystal structure analysis of a porous 3D Hofmann‐like material showed long‐range ordering of spin states: HS, HS0.67LS0.33, HS0.5LS0.5, HS0.33LS0.67, and LS. These detailed structural studies provide insight into how multistep SCO materials can be rationally designed through control of host–host and host–guest interactions.
Four‐step SCO: A porous 3D spin crossover (SCO) framework material that displays a four‐step transition with long‐range ordering of FeII sites is reported. From only one unique site in the high‐spin state, three intermediate phases with individual high‐spin/low‐spin patterns are produced upon cooling to the fully low‐spin state.
An increasing proportion of cognitive difficulties are recognized to have a functional cause, the chief clinical indicator of which is internal inconsistency. When these symptoms are impairing or ...distressing, and not better explained by other disorders, this can be conceptualized as a cognitive variant of functional neurological disorder, termed functional cognitive disorder (FCD). FCD is likely very common in clinical practice but may be under-diagnosed. Clinicians in many settings make liberal use of the descriptive term mild cognitive impairment (MCI) for those with cognitive difficulties not impairing enough to qualify as dementia. However, MCI is an aetiology-neutral description, which therefore includes patients with a wide range of underlying causes. Consequently, a proportion of MCI cases are due to non-neurodegenerative processes, including FCD. Indeed, significant numbers of patients diagnosed with MCI do not 'convert' to dementia. The lack of diagnostic specificity for MCI 'non-progressors' is a weakness inherent in framing MCI primarily within a deterministic neurodegenerative pathway. It is recognized that depression, anxiety and behavioural changes can represent a prodrome to neurodegeneration; empirical data are required to explore whether the same might hold for subsets of individuals with FCD. Clinicians and researchers can improve study efficacy and patient outcomes by viewing MCI as a descriptive term with a wide differential diagnosis, including potentially reversible components such as FCD. We present a preliminary definition of functional neurological disorder-cognitive subtype, explain its position in relation to other cognitive diagnoses and emerging biomarkers, highlight clinical features that can lead to positive diagnosis (as opposed to a diagnosis of exclusion), and red flags that should prompt consideration of alternative diagnoses. In the research setting, positive identifiers of FCD will enhance our recognition of individuals who are not in a neurodegenerative prodrome, while greater use of this diagnosis in clinical practice will facilitate personalized interventions.
MX1 is a bending‐magnet crystallography beamline at the 3 GeV Australian Synchrotron. The beamline delivers hard X‐rays in the energy range from 8 to 18 keV to a focal spot at the sample position of ...120 µm FWHM. The beamline endstation and ancillary equipment facilitate local and remote access for both chemical and biological macromolecular crystallography. Here, the design of the beamline and endstation are discussed. The beamline has enjoyed a full user program for the last seven years and scientific highlights from the user program are also presented.
A photoswitchable ligand based on azobenzene is self‐assembled with palladium(II) ions to form a Pd2(E‐L)44+ cage. Irradiation with 470 nm light results in the near‐quantitative switching to a ...monomeric species Pd(Z‐L)22+, which can be reversed by irradiation with 405 nm light, or heat. The photoswitching selectivity towards the metastable isomer is significantly improved upon self‐assembly, and the thermal half‐life is extended from 40 days to 850 days, a promising approach for tuning photoswitching properties.
A photoswitchable ligand and PdII combine to form a Pd2L44+ coordination cage. The photoswitching selectivity towards the metastable isomer is significantly improved when coordinated, allowing near‐quantitatively photoswitching to a new species, PdL22+. This new species stabilizes the metastable isomer, increasing the thermal half‐life compared to the free ligand.
Covalent post‐synthetic modification is a versatile method for gaining high‐level synthetic control over functionality within porous metal–organic frameworks and for generating new materials not ...accessible through one‐step framework syntheses. Here we apply this topotactic synthetic approach to a porous spin crossover framework and show through detailed comparison of the structures and properties of the as‐synthesised and covalently modified phases that the modification reaction proceeds quantitatively by a thermally activated single‐crystal‐to‐single‐crystal transformation to yield a material with lowered spin‐switching temperature, decreased lattice cooperativity, and altered color. Structure–function relationships to emerge from this comparison show that the approach provides a new route for tuning spin crossover through control over both outer‐sphere and steric interactions.
Changing the switch: Covalent postsynthetic modification (PSM; see picture) of a pillaring ligand in a new porous FeII spin crossover framework occurs with retention of single crystallinity to generate a closely related framework phase that exhibits markedly different switching behaviors (see picture). This conversion establishes covalent modification as a new method for controlling spin crossover in this emerging class of porous multifunctional materials.
Chemical weathering indices are commonly used for characterizing weathering profiles by incorporating bulk major element oxide chemistry into a single metric for each sample. Generally, on ...homogeneous parent rocks, weathering indices change systematically with depth. However, the weathering of heterogeneous metamorphic rocks confounds the relationship between weathering index and depth. In this paper, we evaluate previously defined chemical weathering indices for their suitability in characterizing weathering profiles developed on felsic, heterogeneous, metasedimentary bedrock from Coweeta Hydrologic Laboratory, North Carolina, USA.
Among the weathering indices evaluated here, the Weathering Index of Parker (WIP) is the most appropriate for application to weathering profiles on heterogeneous (and homogeneous) parent rock. Because the WIP includes only the highly mobile alkali and alkaline earth elements in its formulation, it yields values that differ greatly from those of the parent rock. In addition, the WIP allows for aluminum mobility, unlike other weathering indices. These characteristics combine to make the Weathering Index of Parker the most applicable index for studying the weathering of heterogeneous metasedimentary rocks. However, the WIP should be applied judiciously, as alkali and alkaline earth metals may be readily depleted during weathering.
In addition to reflecting weathering, the Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), Plagioclase Index of Alteration (PIA) and Vogt's Residual Index (V) may be sensitive to subtle geochemical changes such as hydrothermal alteration along a fault and/or alteration at the water table. Weathering indices that include iron in their calculations were not included in this study, because they do not distinguish between ferric and ferrous iron. The oxidation state and distribution of iron in a weathering profile is influenced by the proportion of oxidation states in the pre-weathered metamorphic rock and interaction with groundwater during weathering.
A fluxional bis‐monodentate ligand, based on the archetypal shape‐shifting molecule bullvalene, self‐assembles with M2+ (M=Pd2+ or Pt2+) to produce a highly complex ensemble of permanently fluxional ...coordination cages. Metal‐mediated self‐assembly selects for an M2L4 architecture while maintaining shape‐shifting ligand complexity. A second level of simplification is achieved with guest‐exchange; the binding of halides within the M2L4 cage mixture results in a convergence to a cage species with all four ligands present as the “B isomer”. Within this confine, the reaction graph of the bullvalene is greatly restricted, but gives rise to a mixture of 38 possible diastereoisomers in rapid exchange. X‐ray crystallography reveals a preference for an achiral form consisting of both ligand enantiomers. Through a combination of NMR spectroscopy and DFT calculations, we elucidate the restricted isomerisation pathway of the permanently fluxional M2L4 assembly.
The first metallo‐supramolecular M2L4 cages bearing shape‐shifting bullvalene ligands are prepared. The enormous potential complexity is limited by geometric constraints in solution, which converge to a single isomer in the solid state. Through detailed experimental and computational analysis, we map the fluxional nature of these systems.
The incorporation of retention-time information into a fully rotatable and interactive three-dimensional (3D), “Kendrick-like” normalized mass map (NMM) using a single software platform is reported. ...Surprising discoveries were made about the elution pattern of block ethoxylate-propoxylate oligomers (ca. 2800 Da) in the supercritical fluid after combined SFC-Orbitrap FTMS analysis. The 3D NMM also facilitated identification of impurities using interactive graphics tools within the map. By selecting map glyphs, associated reconstructed ion chromatograms were automatically generated. Last, since Kendrick and Kendrick-like mapping (NMM) are chemical-formula-based, incorporating retention time in 3D space allows the possibility of resolving isomers in the map.
Inflammasomes are important for host defence against pathogens and homeostasis with commensal microbes. Here, we show non-haemolytic enterotoxin (NHE) from the neglected human foodborne pathogen ...Bacillus cereus is an activator of the NLRP3 inflammasome and pyroptosis. NHE is a non-redundant toxin to haemolysin BL (HBL) despite having a similar mechanism of action. Via a putative transmembrane region, subunit C of NHE initiates binding to the plasma membrane, leading to the recruitment of subunit B and subunit A, thus forming a tripartite lytic pore that is permissive to efflux of potassium. NHE mediates killing of cells from multiple lineages and hosts, highlighting a versatile functional repertoire in different host species. These data indicate that NHE and HBL operate synergistically to induce inflammation and show that multiple virulence factors from the same pathogen with conserved function and mechanism of action can be exploited for sensing by a single inflammasome.
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