Oxidative Chlorination of Phenols with Hydrogen Chloride/m-Chloroperbenzoic Acid/N,N-Dimethylformamide System

The reaction of phenols with relevant amounts of HCl and m-chloroperbenzoic acid in DMF at room temperature gave regioselective chloro-substituted phenols in good yields.     

Reversible Pore Size Control of Elastic Microporous Material by Mechanical Force

Nanoporous materials, such as zeolites, activated carbons, and metal–organic frameworks (MOFs), are peculiar platforms in which a variety of guest molecules are stored, reacted, and/or separated. The size of the nanopores is essential to realize advanced functions. In this work, we demonstrate a very simple but innovative method for the control of nanopore size, that is, reversible and continuous control by mechanical force loaded to soft nanoporous materials. The elastic properties of several microporous materials, including zeolites, zeolite‐templated carbon (ZTC), activated carbon, and MOFs (e.g., ZIF‐8), are examined and it is found that ZTC is a material that is suitable for the aforementioned idea thanks to its extraordinary soft properties compared to the others. The original pore size of ZTC (1.2 nm) can be contracted to 0.85 nm by using a relatively weak loading force of 135 MPa, whereas the other microporous materials barely contracted. To demonstrate the change in the physical properties induced by such artificial deformation, in situ gas adsorption measurements were performed on ZTC with and without loading mechanical force, by using CO₂, CH₄, and H₂, as adsorbates. Upon the contraction by loading 69 or 135 MPa, CO₂ adsorption amount is increased, due to the deepening of the physisorption potential well inside the micropores, as proved by the increase of the heat of adsorption. Moreover, the adsorption amount is completely restored to the original one after releasing the mechanical force, indicating the fully reversible contraction/recovery of the ZTC framework against mechanical force. The experimental results are theoretically supported by a simulation using Grand Canonical Monte Carlo method. The similar adsorption enhancement is observed also on CH₄, whereas H₂ is found as an exception due to the weak interaction potential.     

The conformations of 13-vertex ML2C2B10 metallacarboranes: experimental and computational studies

The docosahedral metallacarboranes 4,4-(PMe(2)Ph)2-4,1,6-closo-PtC(2)B(10)H(12), 4,4-(PMe(2)Ph)2-4,1,10-closo-PtC(2)B(10)H(12), and [N(PPh(3))2][4,4-cod-4,1,10-closo-RhC(2)B(10)H(12)] were prepared by reduction/metalation of either 1,2-closo-C(2)B(10)H(12) or 1,12-closo-C(2)B(10)H(12). All three species were fully characterized, with a particular point of interest of the latter being the conformation of the {ML2} fragment relative to the carborane ligand face. Comparison with conformations previously established for six other ML(2)C(2)B(10) species of varying heteroatom patterns (4,1,2-MC(2)B(10), 4,1,6-MC(2)B(10), 4,1,10-MC(2)B(10), and 4,1,12-MC(2)B(10)) reveals clear preferences. In all cases a qualitative understanding of these was afforded by simple MO arguments applied to the model heteroarene complexes [(PH3)2PtC(2)B(4)H(6)]2- and [(PH3)2PtCB(5)H(6)]3-. Moreover, DFT calculations on [(PH3)2PtC(2)B(4)H(6)]2- in its various isomeric forms approximately reproduced the observed conformations in the 4,1,2-, 4,1,6-, and 4,1,10-MC(2)B(10) species, although analogous calculations on [(PH3)2PtCB(5)H(6)]3- did not reproduce the conformation observed in the 4,1,12-MC(2)B(10) metallacarborane. DFT calculations on (PH3)2PtC(2)B(10)H(12) yielded good agreement with experimental conformations in all four isomeric cases. Apparent discrepancies between observed and computed Pt-C distances were probed by further refinement of the 4,1,2- model to 1,2-(CH2)3-4,4-(PMe3)2-4,1,2-closo-PtC(2)B(10)H(10). This still has a more distorted structure than measured experimentally for 1,2-(CH2)3-4,4-(PMe(2)Ph)2-4,1,2-closo-PtC(2)B(10)H(10), but the structural differences lie on a very shallow potential energy surface. For the model compound a henicosahedral transition state was located 8.3 kcal mol(-1) above the ground-state structure, consistent with the fluxionality of 1,2-(CH2)3-4,4-(PMe(2)Ph)2-4,1,2-closo-PtC(2)B(10)H(10) in solution.     

A novel thiol compound, N-acetylcysteine amide, attenuates allergic airway disease by regulating activation of NF-kappaB and hypoxia-inducible factor-1alpha

Reactive oxygen species (ROS) play an important role in the pathogenesis of airway inflammation and hyperresponsiveness. Recent studies have demonstrated that antioxidants are able to reduce airway inflammation and hyperreactivity in animal models of allergic airway disease. A newly developed antioxidant, small molecular weight thiol compound, N-acetylcysteine amide (AD4) has been shown to increase cellular levels of glutathione and to attenuate oxidative stress related disorders such as Alzheimer's disease, Parkinson's disease, and multiple sclerosis. However, the effects of AD4 on allergic airway disease such as asthma are unknown. We used ovalbumin (OVA)-inhaled mice to evaluate the role of AD4 in allergic airway disease. In this study with OVA-inhaled mice, the increased ROS generation, the increased levels of Th2 cytokines and VEGF, the increased vascular permeability, the increased mucus production, and the increased airway resistance in the lungs were significantly reduced by the administration of AD4. We also found that the administration of AD4 decreased the increases of the NF-kappaB and hypoxia-inducible factor-1alpha (HIF-1alpha) levels in nuclear protein extracts of lung tissues after OVA inhalation. These results suggest that AD4 attenuates airway inflammation and hyperresponsiveness by regulating activation of NF-kappaB and HIF-1alpha as well as reducing ROS generation in allergic airway disease.     

Form III of 2,2′,4,4′,6,6′‐hexanitro­azobenzene (HNAB‐III)

The crystal structure of form III of the title compound, HNAB [systematic name: bis(2,4,6‐trinitro­phenyl)diazene], C₁₂H₄N₈O₁₂, has finally been solved as a pseudo‐merohedral twin (monoclinic space group P2₁, rather than the ortho­rhombic space group C222₁ suggested by diffraction symmetry) using a dual space recycling method. The significant differences in the room‐temperature densities of the three crystalline forms allow examination of molecular differences due to packing arrangements. An interesting relationship with the stilbene analog, HNS, is discussed. Interatomic separations are compared with other explosives and/or nitro‐containing compounds.     

A two-photon fluorescent probe for ratiometric imaging of hydrogen peroxide in live tissue

We report a two-photon fluorescent probe (PN1) that can be excited by 750 nm femto-second pulses, shows high photostability and negligible toxicity, and can visualize H(2)O(2) distribution in live cells and tissue by two-photon microscopy.     

A Comparison of 3 Digital Image Correlation Techniques on Necessarily Suboptimal Random Patterns Recorded By X-Ray

Dynamic x-rays have been used to follow the deformation ahead of a steel ball fired into a mock-up of a generic cylindrical rocket motor. The impact was arranged to intersect a sparse lead powder layer within the mock explosive that created a random speckle pattern on x-ray film. Three different digital image correlation programs are compared to examine any sensitivity to the sub-optimal speckle pattern produced by the lead powder. An identical output data reduction method was used in all cases to aid comparison. All three correlation methods were able analyze the deformation, but all had intricacies that would require more detailed optimization of the data reduction in order to fully exploit the technique. Quantitative analysis showed that the three methods agreed closely in estimations of rigid body displacements between a pair of representative x-ray images. It was discovered that the deformation caused by the ball impact was highly localized and the useful data available about the deformation pattern was sparse. This limits the applicability of this technique to this specific application. Extensive cracking was not observed that would have aided the development of computer-based models for prediction of such impact events. The x-ray technique was however excellent for determining the ball position as a function of time after impact.