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The development of heterogeneous catalyst systems for enantioselective reactions is an important subject in modern chemistry as they can be easily separated from products and potentially reused; this is particularly favorable in achieving a more sustainable society. Whereas numerous homogeneous chiral small molecule catalysts have been developed to date, there are only limited examples of heterogeneous ones that maintain high activity and have a long lifetime. On the other hand, metal nanoparticle catalysts have attracted much attention in organic chemistry due to their robustness and ease of deposition on solid supports. Given these advantages, metal nanoparticles modified with chiral ligands, defined as "chiral metal nanoparticles", would work efficiently in asymmetric catalysis. Although asymmetric hydrogenation catalyzed by chiral metal nanoparticles was pioneered in the late twentieth century, the application of chiral metal nanoparticle catalysis for asymmetric C-C bond-forming reactions that give a hign bonding. This chiral diene was very effective for the Rh/Ag nanoparticle-catalyzed asymmetric arylation of various electron-deficient olefins, including enones, unsaturated esters, unsaturated amides and nitroolefins, and imines to afford the corresponding products in excellent yields and with outstanding enantioselectivities. The system was also applicable for the synthesis of intermediates of various useful compounds. Furthermore, the compatibility of chiral Rh nanoparticles with other catalysts was confirmed, enabling the development of tandem reaction systems and cooperative catalyst systems.The nature of the active species was investigated. Several characteristic features of the heterogeneous nanoparticle systems that were completely different from those of the corresponding homogeneous metal complex systems were found.The application of Li-ion conducting garnet electrolytes is challenged by their large interfacial resistance with the metallic lithium anode and the relative small critical current density at which the lithium dendrites short-circuit the battery. Both of these challenges are closely related to the morphology and the structure of the garnet membranes. Here, we prepared four polycrystalline garnet Li6.4La3Zr1.4Ta0.6O12 (LLZTO) pellets with different particle sizes (nano/micro) and grain boundary additive (with/without Al2O3) to investigate the influence of grain size, the composition of the grain boundary, and the mechanical strength of the pellet on the total Li-ion conduction of the pellet, Li/garnet interfacial transfer, and lithium dendrite growth in all-solid-state Li-metal cells. The results showed that the garnet pellets prepared with nanoparticles and LiAlO2-related grain boundary phase had decreased total Li-ion conductivity because of the increased resistance of the grain boundary; however, these pellets showed higher mechanical strength and improved capability to suppress lithium dendrite growth at high current densities. By controlling the grain size and optimizing the grain boundary with Al2O3 sintering additive, the hot-pressing sintered LLZTO solid electrolytes can reach up to 1.01 × 10-3 S cm-1 in Li+ conductivity and 0.29 eV in activation energy. LLZTO with nanosized grain and LiAlO2-modified grain boundary showed the highest critical current density, which is 0.6 mA cm-2 at room temperature and 1.7 mA cm-2 at 60 °C. This study offers a useful guideline for preparing a high-performance LLZTO solid electrolyte.Magnetic nanostructures (MNS) have a wide range of biological applications due to their biocompatibility, superparamagnetic properties, and customizable composition that includes iron oxide (Fe3O4), Zn2+, and Mn2+. However, several challenges to the biomedical usage of MNS must still be addressed, such as formulation stability, inability to encapsulate therapeutic payloads, and variable clearance rates in vivo. Here, we enhance the utility of MNS during controlled delivery applications via encapsulation within polymeric bicontinuous nanospheres (BCNs) composed of poly(ethylene glycol)-block-poly(propylene sulfide) (PEG-b-PPS) copolymers. PEG-b-PPS BCNs have demonstrated versatile encapsulation and delivery capabilities for both hydrophilic and hydrophobic payloads due to their unique and highly organized cubic phase nanoarchitecture. MNS-embedded BCNs (MBCNs) were thus coloaded with physicochemically diverse molecular payloads using the technique of flash nanoprecipitation and characterized in terms of their se on-demand and sustained drug delivery applications.We report a facile synthesis of a thiolate-protected water-soluble ultrasmall cubic copper nanocluster-based metal-organic framework (CuMOF) as an efficient and chemoselective catalyst for the azide-alkyne click reaction. MK0683 Interestingly, the diffuse reflectance spectra of CuMOFs exhibit three discrete plasmon bands at 463, 505, and 674 nm, which are similar to those corresponding to the fingerprint region of thiolate-protected atomically precise Au25 nanoclusters; hence, CuMOFs are termed as gold-like ultrasmall cubic copper nanoclusters. The high-resolution transmission electron microscopy (HRTEM) and powder X-ray diffraction (XRD) patterns confirm the cubic morphology of CuMOFs with nanoclusters showing particle size distribution of ∼2-12 nm. The matrix-assisted laser desorption ionization (MALDI) spectrum of CuMOFs is attributed to the individual particles consisting of few Cu n (SR) m with Cu(0) core atoms and Cu(I)SR staples, i.e., Cu2(SR)4, Cu(SR)6, Cu3(SR)7, and Cu4(SR)8. To our surprise, the unsymmetric bistriazoles resulting from the click reaction of bifunctional azides and alkynes in the presence of CuMOFs were achieved by step-by-step conversion of the terminal azide selectively with maximum yield in the range of 70-88%. The nitrogen adsorption-desorption studies confirm the size-dependent surface area, pore volume, and pore size for the CuMOFs prepared by varying metal-to-ligand ratios. The plausible mechanism for the selective mono-click at CuMOFs suggests the existence of bifunctional terminal interactions via thiol and sulfonate groups that might have provided the site-isolation-based active sites for selective catalysis. The easy recovery of CuMOFs and their reusability up to 5 times without significant loss of activity are very promising for the selective organic conversions in pharmaceutical and industrial formulations.
My Website: https://www.selleckchem.com/products/Vorinostat-saha.html
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