Naphthalic anhydride derivatives: Structural effects on their initiating abilities in radical and/or cationic photopolymerizations under visible light

Only one naphthalic anhydride derivative has been reported as light sensitive photoinitiator, this prompted us to further explore the possibility to prepare a new family of photoinitiators based on this scaffold. Therefore, eight naphthalic Naphthalic anhydride derivatives (ANH1‐ANH8) have been prepared and combined with an iodonium salt (and optionally N‐vinylcarbazole) or an amine (and optionally 2,4,6‐tris(trichloromethyl)‐1,3,5‐triazine) to initiate the cationic polymerization of epoxides and the free radical polymerization of acrylates under different irradiation sources, that is, very soft halogen lamp (～ 12 mW cm^?2), laser diode at 405 nm (～1.5 mW cm^?2) or blue LED centered at 455 nm (80 mW cm^?2). The ANH6 based photoinitiating systems are particularly efficient for the cationic and the radical photopolymerizations, and even better than that of the well‐known camphorquinone based systems. The photochemical mechanisms associated with the chemical structure/photopolymerization efficiency relationships are studied by steady state photolysis, fluorescence, cyclic voltammetry, laser flash photolysis, and electron spin resonance spin‐trapping techniques. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2860–2866     

Deficiency of optineurin enhances osteoclast differentiation by attenuating the NRF2-mediated antioxidant response

Abnormally increased resorption contributes to bone degenerative diseases such as Paget’s disease of bone (PDB) through unclear mechanisms. Recently, the optineurin (OPTN) gene has been implicated in PDB, and global OPTN knockout mice (Optn^−/−) were shown to exhibit increased formation of osteoclasts (osteoclastogenesis). Growing evidence, including our own, has demonstrated that intracellular reactive oxygen species (ROS) stimulated by receptor activator of nuclear factor kappa-B ligand (RANKL) can act as signaling molecules to promote osteoclastogenesis. Here, we report that OPTN interacts with nuclear factor erythroid-derived factor 2-related factor 2 (NRF2), the master regulator of the antioxidant response, defining a pathway through which RANKL-induced ROS could be regulated for osteoclastogenesis. In this study, monocytes from Optn^−/− and wild-type (Optn^+/+) mice were utilized to differentiate into osteoclasts, and both qRT-PCR and tartrate-resistant acid phosphatase (TRAP) staining showed that the Optn^−/− monocytes exhibited enhanced osteoclastogenesis compared to the Optn^+/+ cells. CellROX^® staining, qRT-PCR, and Western blotting indicated that OPTN deficiency reduced the basal expression of Nrf2, inhibited the expression of NRF2-responsive antioxidants, and increased basal and RANKL-induced intracellular ROS levels, leading to enhanced osteoclastogenesis. Coimmunoprecipitation (co-IP) showed direct interaction, and immunofluorescence staining showed perinuclear colocalization of the OPTN-NRF2 granular structures during differentiation. Finally, curcumin and the other NRF2 activators attenuated the hyperactive osteoclastogenesis induced by OPTN deficiency. Collectively, our findings reveal a novel OPTN-mediated mechanism for regulating the NRF2-mediated antioxidant response in osteoclasts and extend the therapeutic potential of OPTN in the aging process resulting from ROS-triggered oxidative stress, which is associated with PDB and many other degenerative diseases.Subject terms: Mechanisms of disease, Stress signalling     

Catalytic Adventures in Space and Time Using High Energy X-rays

Very high energy X-rays (ca. >40 keV) have long offered great promise in providing great insight into the inner workings of catalysts; insights that may complement the battery of techniques available to researchers in catalysis either in the laboratory or at more conventional X-ray wavelengths. This contribution aims to critically assess the diverse possibilities now available in the high energy domain as a result of the maturation of third generation synchrotron facilities and to look forward to the potential that forthcoming developments in synchrotron source technology may offer the world of catalysis in the near future.     

Michael addition of 1,3-dicarbonyl compounds catalyzed by iron oxide nanoparticles

Several iron oxides nanoparticles (Fe₂O₃@Fe₂O₃, Fe°@Fe₂O₃, GO@Fe₂O₃ and calcinated Fe₂O₃) have been assessed as catalysts in the 1,4-addition of a cyclic β-ketoester onto methyl vinyl ketone under neat conditions. It appeared that calcinated Fe₂O₃NP are efficient catalysts at 1?mol% loading for the Michael addition of 1,3-dicarbonyl compounds onto various enones.     

Influence of the formulation of catalysts deposited on cordierite monoliths for acetic acid oxidation

Monolithic catalysts are prepared by washcoating cordierite monoliths with different sols (Pt/Al₂O₃, Pt/CeO₂, Pt/ZrO₂, Pt/Al₂O₃CeO₂, Pt/Al₂O₃ZrO₂, and Pt/CeO₂ZrO₂). These sols are prepared by a sol–gel process and characterized by specific surface area (S_BET), inductively coupled plasma, hydrogen chemisorption, high-resolution transmission electron microscopy, field emission scanning electron microscopy, oxygen storage capacity, X-ray diffraction, temperature-programmed reduction, CO₂ chemisorption, and the model reaction of 3,3-dimethylbutene isomerization. The catalytic performances of the monolithic catalysts are then evaluated for the acetic acid oxidation. The nature of catalyst coating has been found to influence the adherence with the cordierite monolith and the presence of cerium in the catalyst appears to increase the adherence of the latter. Pt/CeO₂, Pt/Al₂O₃CeO₂, and Pt/CeO₂ZrO₂ are found to be the most reducible catalysts (oxygen storage capacity and temperature-programmed reduction) and to have the lowest acidities (3,3-dimethylbutene isomerization). CO₂ chemisorption shows that these catalysts possess a good basicity. From the relation established between the catalytic activity and the redox and acid–base properties it has been concluded that the reducibility is the key factor for a good catalytic activity although the basicity has a significant influence on the catalytic performance.     

Investigation of alkali borosilicate glass durability using tritium tracing, β-autoradiography, scanning electron microscopy and ion beam analysis

A Li-Na-containing borosilicate glass was submitted to aqueous corrosion in static mode in tritiated solutions of various pH at room temperature and 90 °C. Tritium counting, β-autoradiography, scanning electron microscopy (SEM) and ion beam analysis (IBA) techniques have been used to investigate the composition variations of the leached glass surfaces. In an acidic medium, the glass surface is covered by a thick hydrated silica layer; mobile elements like Li, Na and B and transition elements like Fe and Mo are strongly depleted. Near pH 7, relative enrichments of aluminium and iron are shown together with strong Li, Na and B depletions. In a basic medium, the glass surface exhibits iron and molybdenum enrichments whereas mobile elements seem to be kept at their nominal concentration level at the glass surface. The tritium activity and distribution on the leached glass surface is shown to depend strongly on the pH of the tritiated solutions. These observations are correlated with the observed changes of the surface morphology and chemistry characterized by IBA and SEM analysis. Elemental solubility versus pH of various chemical species have been calculated for comparison purpose with the experimental observations.     

Second-generation tags for fluorous chemistry exemplified with a new fluorous Mitsunobu reagent

A new fluorous DEAD reagent bearing two perfluoro-tert-butyloxy groups with propylene spacers shows excellent promise for use in fluorous Mitsunobu reactions. Pure target products were obtained in good yields after removing fluorous byproducts by FSPE. The new reagent serves as a prototype for a greener second generation of fluorous reagents bearing tags that are not expected to degrade in the environment to compounds that are highly persistent or that bioaccumulate in higher organisms.     

Direct C-glycosylation by indium-mediated alkynylation on sugar anomeric position

Indium-mediated alkynylation reaction was studied for the direct preparation of C-glycosides. Easily available starting sugar derivatives with an acetyl group at the anomeric position were tested as electrophiles toward alkynylindium reagents under Barbier conditions. Good yields and stereoselectivities were observed during the reaction. The alkynylation was applied to the synthesis of an alpha-(1-->6)-C-disaccharide analogue of isomaltoside.