Schmittspencer2276

Chiral α-branched amines are common structural motifs in functional materials, pharmaceuticals, and chiral catalysts. Therefore, developing efficient methods for preparing compounds with these privileged scaffolds is an important endeavor in synthetic chemistry. Herein, we describe an atom-economical, modular method for a nickel-catalyzed enantioselective α-alkenylation of readily available linear N-sulfonyl amines with alkynes to afford a wide variety of allylic amines without the need for exogenous oxidants, reductants, or activating reagents. The method provides a platform for constructing chiral α-branched amines as well as derivatives such as α-amino amides and β-amino alcohols, which can be conveniently accessed from the newly introduced alkene. Given the generality, versatility, and high atom economy of this method, we anticipate that it will have broad synthetic utility.Controlled patterning of nanoparticles on bioassemblies enables synthesis of complex materials for applications in optics, nanoelectronics, and sensing. Biomolecular self-assembly offers molecular control for engineering patterned nanomaterials, but current approaches have been limited in their ability to combine high nanoparticle coverage with generality that enables incorporation of multiple nanoparticle types. Here, we synthesize photonic materials on crystalline two-dimensional (2D) protein sheets using orthogonal bioconjugation reactions, organizing quantum dots (QDs), gold nanoparticles (AuNPs), and upconverting nanoparticles along the surface-layer (S-layer) protein SbsB from the extremophile Geobacillus stearothermophilus. We use electron and optical microscopy to show that isopeptide bond-forming SpyCatcher and SnoopCatcher systems enable the simultaneous and controlled conjugation of multiple types of nanoparticles (NPs) at high densities along the SbsB sheets. These NP conjugation reactions are orthogonal to each other and to Au-thiol bond formation, allowing tailorable nanoparticle combinations at sufficient labeling efficiencies to permit optical interactions between nanoparticles. Fluorescence lifetime imaging of SbsB sheets conjugated to QDs and AuNPs at distinct attachment sites shows spatially heterogeneous QD emission, with shorter radiative decays and brighter fluorescence arising from plasmonic enhancement at short interparticle distances. This specific, stable, and efficient conjugation of NPs to 2D protein sheets enables the exploration of interactions between pairs of nanoparticles at defined distances for the engineering of protein-based photonic nanomaterials.LaF3 and NaLaF4 crystals were selectively precipitated in the SiO2-Al2O3-AlF3-Na2O-NaF-LaF3-ErF3 glass system by adjusting their compositions. The structural evolution at the atomic level driven by heat treatment and glass compositions was studied using the state-of-the-art magic-angle spinning nuclear magnetic resonance technique. From a comprehensive local structural study, we found that LaF3 and NaLaF4 crystals compete in crystallization in these glasses. The crystallization ability of NaLaF4 increases with the increase of the content of Na+ ions within the F-enriched phase, but for LaF3 crystals, it is reverse. These two crystals can be selectively precipitated in the glasses by adjusting the content of these Na+ ions within the F-enriched phase. When the crystallization ability of these two crystals becomes similar, none of them can be precipitated due to their mutual interference in crystallization. Intense single green upconversion luminescence occurs in glasses precipitating LaF3 or NaLaF4 crystals. The underlying relationship between compositions, structures, crystallization, and upconversion luminescence properties is unearthed based on the structural evolution, crystallization mechanism, and luminescence properties. This relationship will facilitate the compositional design of these kinds of glasses. It is inferred that it will be better to precipitate LaF3 rather than NaLaF4 crystals for achieving highly efficient upconversion luminescence.The combination of (AlCp*)4, a source of monomeric AlCp* at elevated temperatures, with DipTerPnPMe3 (Pn = P, As), so-called pnicta-Wittig reagents, at 80 °C cleanly gives the pnictaalumenes DipTerPnAlCp* with polarized Pn-Al double bonds and intramolecular stabilization through interactions of Al with a flanking aryl group of the terphenyl substituent on Pn. In contrast, using MesTerPPMe3, the reaction with 2 equiv of AlCp3t or AlCp* afforded the three-membered 2π-aromatic ring systems MesTerP(AlCp x )2 (x = 3t, *).Single and a few atomic-layer molybdenum disulfide (MoS2) is a promising material in the fields of hydrogen generation, battery, supercapacitor, and environmental protection, owing to the outstanding electronic, optical, and catalytic properties. Although many approaches have been developed for exfoliation of MoS2 sheets, it is still essential to develop simple, convenient, and environmental friendly exfoliation methods. More importantly, the microscopic exfoliation process and the mechanism are still not clear, limiting a deeper understanding of the exfoliation. Herein, we develop a convenient and clean method for exfoliation of the 2H phase MoS2 (2H-MoS2) deposited on an indium tin oxide (ITO) surface. Importantly, the exfoliation process is observed directly and continuously under an optical microscope to reveal the detailed exfoliation process and mechanism. As illustrated, the light illumination triggers the exfoliation of the 2H-MoS2 sheets, and the presence of water is essential in this exfoliation process. GS-9973 purchase The light intensity and wavelength, humidity, and bias all affect the exfoliation process obviously. The exfoliation is caused by the vaporization of the water molecules intercalated in 2H-MoS2 interlayers. By using this method, 2H-MoS2 nanosheets with different thicknesses are prepared on the ITO substrate, and microscopic catalysis mapping of the exfoliated sheets is demonstrated with single-molecule fluorescence microscopy, revealing that the prepared thin-layer 2H-MoS2 nanosheets show improved electrocatalysis activity (roughly 20 times). Our work will not only help deepen the understanding of exfoliation process of two-dimensional nanosheets but also provide an effective tool for the in situ study of various properties of the exfoliated sheets.