Hetero-interpenetrated metal-organic frameworks.

Interpenetrated metal-organic frameworks (MOFs) comprise two or more lattices that are mutually entangled. Interpenetration can be used to tune the structures and pore architectures of MOFs to influence, for example, their stability or interactions with guest molecules. The interpenetrating sublattices are typically identical, but hetero-interpenetrated MOFs, which consist of sublattices that are different from one another, have also been serendipitously produced. Here we describe a strategy for the deliberate synthesis of hetero-interpenetrated MOFs. We use the cubic α-MUF-9 framework as a host sublattice to template the growth of a second sublattice within its pores. Three different secondary sublattices are grown-two of which are not known as standalone MOFs-leading to three different hetero-interpenetrated MOFs. This strategy may serve to combine different properties into one material. We produce an asymmetric catalysis by allocating separate roles to the interpenetrating sublattices in a hetero-interpenetrated MOF: an achiral secondary amine on one sublattice provides the catalytic activity, while the chiral α-MUF-10 host imparts asymmetry to aldol and Henry reactions.

Multicomponent Metal-Organic Frameworks.

Metal-organic frameworks (MOFs) are constructed from metal ions or clusters and organic linkers. Typical MOFs are rather simple, comprising just one type of joint and linker. An additional degree of structural complexity can be introduced by using multiple different components that are assembled into the same framework In the early days of MOF chemistry, conventional wisdom held that attempting to prepare frameworks starting from such a broad set of components would lead to multiple different phases. However, this review highlights how this view was mistaken and frameworks comprising multiple different components can be deliberately designed and synthesized. When coupled to structural order and periodicity, the presence of multiple components leads to exceptional functional properties that can be understood at the atomic level.

Enhancing Multicomponent Metal-Organic Frameworks for Low Pressure Liquid Organic Hydrogen Carrier Separations.

The resurgence of interest in the hydrogen economy could hinge on the distribution of hydrogen in a safe and efficient manner. Whilst great progress has been made with cryogenic hydrogen storage or liquefied ammonia, liquid organic hydrogen carriers (LOHCs) remain attractive due to their lack of need for cryogenic temperatures or high pressures, most commonly a cycle between methylcyclohexane and toluene. Oxidation of methylcyclohexane to release hydrogen will be more efficient if the equilibrium limitations can be removed by separating the mixture. This report describes a family of six ternary and quaternary multicomponent metal-organic frameworks (MOFs) that contain the three-dimensional cubane-1,4-dicarboxylate (cdc) ligand. Of these MOFs, the most promising is a quaternary MOF (CUB-30), comprising cdc, 4,4'-biphenyldicarboxylate (bpdc) and tritopic truxene linkers. Contrary to conventional wisdom that adsorptive interactions with larger, hydrocarbon guests are dominated by π-π interactions, here we report that contoured aliphatic pore environments can exhibit high selectivity and capacity for LOHC separations at low pressures. This is the first time, to the best of our knowledge, where selective adsorption for cyclohexane over benzene is witnessed, underlining the unique adsorptive behavior afforded by the unconventional cubane moiety.

Abrupt spin crossover in iron(iii) complexes with aromatic anions.

Two iron(iii) spin crossover complexes, [Fe(qsal-X)2]OTs·nH2O, (Br 1·H2O; I, 2·2H2O or non-solvated 1, 2) have been prepared and fully characterized. Structural studies of 1·H2O and 2·2H2O reveal the presence of 1D π-π chains linking the Fe(iii) centres and a strong XO halogen bond. In both complexes the 1D π-π chains are angled relative to each other, enforced by C-HX interactions. Magnetic studies reveal abrupt spin crossover in 1 (T1/2↓ = 258 K and T1/2↑ = 260 K) and 2 (T1/2 = 298 K) with T1/2 increasing on going from Br to I. The presence of abrupt spin crossover in both complexes shows that aromatic anions can be effective in the design of cooperative spin crossover systems.

The First Observation of Hidden Hysteresis in an Iron(III) Spin-Crossover Complex.

Molecular magnetic switches are expected to form the functional components of future nanodevices. Herein we combine detailed (photo-) crystallography and magnetic studies to reveal the unusual switching properties of an iron(III) complex, between low (LS) and high (HS) spin states. On cooling, it exhibits a partial thermal conversion associated with a reconstructive phase transition from a [HS-HS] to a [LS-HS] phase with a hysteresis of 25 K. Photoexcitation at low temperature allows access to a [LS-LS] phase, never observed at thermal equilibrium. As well as reporting the first iron(III) spin crossover complex to exhibit reverse-LIESST (light-induced excited spin state trapping), we also reveal a hidden hysteresis of 30 K between the hidden [LS-LS] and [HS-LS] phases. Moreover, we demonstrate that FeIII spin-crossover (SCO) complexes can be just as effective as FeII systems, and with the advantage of being air-stable, they are ideally suited for use in molecular electronics.

Delta neutrophil index as an early predictive marker of severe acute pancreatitis in the emergency department.

Background: Predicting severe acute pancreatitis (AP) in the early clinical stage is important for low morbidity and mortality. Delta neutrophil index (DNI) is used to detect infection and inflammation, but no previous studies have evaluated the usefulness of DNI as an early predictor of progression to severe AP (SAP). Methods: The medical records of patients who were diagnosed with AP at the emergency department (ED) of Wonju Severance Christian Hospital from January 2012 to August 2016 were retrospectively reviewed. The initial DNI obtained in the ED was compared with other inflammatory markers to predict SAP. Multivariate logistic regression was used for statistical analysis. Results: Of the 209 cases included in the analysis, 13 were classified as SAP. Compared to the DNI of the mild to moderately SAP group, that in the SAP group was considerably higher. The DNI showed a positive correlation with the Atlanta classification and bedside index of severity in AP. Using multivariate logistic regression analysis, DNI was an independent predictor of early SAP detection (odds ratio 1.122, 95% CI 1.045-1.205, p = 0.001). Among the biomarkers, DNI had the highest predictive value for SAP. Conclusions: The DNI measured in the ED at presentation is a potentially useful adjunctive marker to predict SAP.

Catalysts Confined in Programmed Framework Pores Enable New Transformations and Tune Reaction Efficiency and Selectivity.

Controlling chemical reactions in porous heterogeneous catalysts is a tremendous challenge because of the difficulty in producing uniform active sites that can be tuned with precision. However, analogous to enzymes, when a catalytic pocket provides complementary close contacts and favorable intermolecular interactions with the reaction participants, the reaction efficiency and selectivity may be tuned. Here, we report an isoreticular family of catalysts based on the multicomponent metal-organic framework MUF-77. The microenvironment around the site of catalysis was successfully programmed by introducing functional groups (modulators) to the organic linkers at sites remote from the catalytic unit. The framework catalysts produced in this way exhibit several unique features, including the simultaneous enhancement of both reactivity and stereochemical selectivity in aldol reactions, the ability to catalyze Henry reactions that cannot be accomplished by homogeneous analogs, and discrimination between different reaction pathways (Henry versus aldol) that compete for a common substrate.

Metal-organic framework glasses with permanent accessible porosity.

To date, only several microporous, and even fewer nanoporous, glasses have been produced, always via post synthesis acid treatment of phase separated dense materials, e.g. Vycor glass. In contrast, high internal surface areas are readily achieved in crystalline materials, such as metal-organic frameworks (MOFs). It has recently been discovered that a new family of melt quenched glasses can be produced from MOFs, though they have thus far lacked the accessible and intrinsic porosity of their crystalline precursors. Here, we report the first glasses that are permanently and reversibly porous toward incoming gases, without post-synthetic treatment. We characterize the structure of these glasses using a range of experimental techniques, and demonstrate pores in the range of 4 - 8 Å. The discovery of MOF glasses with permanent accessible porosity reveals a new category of porous glass materials that are elevated beyond conventional inorganic and organic porous glasses by their diversity and tunability.

Lenticular fibroxanthomatous nodule.

PURPOSE: To describe two patients with unique lenticular nodular proliferations. DESIGN: Observational case reports. METHODS: The clinical histories and pathologic findings of two patients with lenticular nodular proliferations were reviewed. RESULTS: One patient with persistent hyperplastic primary vitreous and another patient with trauma developed lenticular nodular proliferations. The nodules were vascularized collections of foamy histiocytes, multinucleated cells, lens capsule, and lens epithelium that had undergone fibrous metaplasia. The lesions were classified as lenticular fibroxanthomatous nodules. CONCLUSIONS: A lenticular fibroxanthomatous nodule is a unique clinicopathologic entity that should be differentiated from Soemmerring ring, Elschnig pearl, and other simulating entities such as juvenile xanthogranuloma.