Borgschmitt5379

Electrides, accommodating excess electrons in lattice voids as anions, have attracted considerable attention in both fundamental research and application development because of their interesting properties, such as ultralow work functions, high electronic mobility, high catalytic activity, and anisotropic electronic and optical properties. Recently, much research progress has been made in both types and applications of inorganic electrides because of the high stability. In this Perspective, we aim to summarize the recent development of inorganic electrides discovered and proposed by experiment and theoretical calculations, highlighting the main applications, including catalysis, metal-ion batteries, superconductivity, magnetism, and organic light-emitting diodes. We provide insights into the role of anionic electrons in electrides playing in the stability and properties. Finally, the problems, challenges, and opportunities are presented, which provide an outlook for future research.Property-oriented material design is a persistent pursuit for material scientists. Recently, machine learning (ML) as a powerful new tool has attracted worldwide attention in the material design field. Based on statistics instead of solving physical equations, ML can predict material properties faster with lower cost. Because of its data-driven characteristics, the quantity and quality of material data become the keys to the practical applications of this technique. In this Perspective, problems caused by lack of data and diversity of data are discussed. Various approaches, including high-throughput calculations, database construction, feedback loop algorithms, and better descriptors, have been exploited to address these problems. It is expected that this Perspective will bring data itself to the forefront of ML-based material design.Seeking to selectively functionalize natural and synthetic amphiphiles, we explored acylation of model amphiphilic diols. The use of a nucleophilic catalyst enabled a remarkable shift of the site selectivity from the polar site, preferred in background noncatalyzed or base-promoted reactions, to the apolar site. This tendency was significantly enhanced for organocatalysts comprising an imidazole active site surrounded by long/branched tails. An explanation of these orthogonal modes of selectivity is supported by competitive experiments with monoalcohol substrates.Pd(II)-catalyzed C-H lactonization of o-methyl benzoic acid substrates has been achieved using molecular oxygen as the oxidant. This finding provides a rare example of C-H oxygenation through Pd(II)/Pd(0) catalysis as well as a method to construct biologically important benzolactone scaffolds. The use of a gas mixture of 5% oxygen in nitrogen demonstrated the possibility for its application in pharmaceutical manufacturing.Hybrid plasmonic metamaterials offer a pathway to exotic properties and technologically important applications including subdiffraction imaging and plasmonic energy harvesting. Challenges remain for practical applications including high absorption losses of noble metals and tedious growth/fabrication processes. In this work, a self-assembled hybrid plasmonic metamaterial consisting of anisotropic AgxAu1-x alloy nanopillars embedded in a ZnO matrix has been successfully grown. The chemical composition of the nanoalloy was determined to be Ag61Au39. The microstructure and optical properties arising from ZnO-Ag61Au39 alloyed hybrid systems were investigated and compared with that of the ZnO-Ag particle-in-matrix nanocomposite and the ZnO-Au vertically aligned nanocomposite. The ZnO-Ag61Au39 hybrid system demonstrates anisotropic morphology, excellent epitaxial quality, and enhanced optical properties, including surface plasmon resonance, hyperbolic dispersion, low absorption losses, and numerous epsilon-near-zero permittivity points, making it a promising candidate for practical applications of hybrid plasmonic metamaterials.The asymmetric reduction of β-keto-γ-acetal enamides has been investigated. A wide range of enantioenriched β-hydroxy-γ-acetal enamides were obtained through asymmetric transfer hydrogenation catalyzed by a tethered Rh(III)-DPEN complex with yields up to quantitative and enantioselectivities up to 99%. The reaction proved to be highly chemoselective toward the reduction of the carbonyl group over the C═C bond.Recently, it has been estimated that nearly 200 million people use marijuana with growing usage being attributed to the legalization and decriminalization of the drug around the world. A concerning implication of increased marijuana use is the alarming number of individuals who report driving under the influence of the drug, which has prompted the development of detection technologies. An electrochemical-based detection technology, akin to how the alcohol breathalyzer functions, would provide an attractive solution to this growing societal problem. The first step toward this goal is to develop a reaction that converts Δ9-tetrahydrocannabinol (Δ9-THC), the primary psychoactive substance in marijuana, to a derivative with diagnostic spectroscopic changes. We report the development of a mild electrochemical method for the oxidation of Δ9-THC to its corresponding p-quinone isomer. The photophysical and electrochemical properties of the resultant quinone show a dramatic shift in comparison to Δ9-THC. This simple protocol provides the foundation for the development of an electrochemical-based marijuana breathalyzer.NaCl is one of the simplest compounds and was thought to be well-understood, and yet, unexpected complexities related to it were uncovered at high pressure and in low-dimensional states. Here, exotic hexagonal NaCl thin films on the (110) diamond surface were crystallized in the experiment following a theoretical prediction based on ab initio evolutionary algorithm USPEX. State-of-the-art calculations and experiments showed the existence of a hexagonal NaCl thin film, which is due to the strong chemical interaction of the NaCl film with the diamond substrate.(Thio)urea cocatalyst accelerates O-monoacyltartaric acid (MAT)-catalyzed enantioselective conjugate addition of boronic acid to unsaturated ketone. Kinetic studies of this reaction revealed first-order dependence of each substrate and catalyst and second-order dependence of (thio)urea, leading to reduction of the catalyst loading and development of more active and enantioselective MAT monoaryl ester catalyst.Halogen lamp irradiation of benzo[e][1,2,4]triazines 2[X] in CH2Cl2 solutions leads to planar ring-fused 1,4-dihydro[1,2,4]triazin-4-yl radicals 1 through a novel, potentially general, cyclization mechanism. The scope and efficiency of the method were established for unsubstituted and ortho-substituted (X = NH2, Br, NO2) phenoxy, naphthyloxy, and quinolinoxy derivatives 2[X]. The regioselectivity of 2[X] photocyclization was rationalized with DFT computational methods. Radicals 1 were characterized by spectroscopic (UV-vis, EPR), electrochemical, and XRD methods.A variety of cyclopropyl aryl ketones undergo uncatalyzed cascade ring-opening/recyclization reactions to generate indenones and fluorenones. In addition, a new strategy to access 3-hydroxyindanones possessing two contiguous stereogenic centers, one of them being an all-carbon quaternary center, was also established. During the course of the investigation, pronounced solvent, temperature, and substituent effects on the product distribution were discovered.Surface and tip-enhanced Raman spectroscopies in total internal reflection (TIR-SERS and TIR-TERS) are used to characterize the oxidation, spin, and ligation state of cytochrome c (Cc) molecules electrostatically bound on a hydrophilic thiol self-assembled monolayer. TIR-SERS spectra of this model hemoprotein show marker bands typical of the 6cLS ferric state of Cc. The performances of the TIR-TERS technique as a function of the incidence angle are described, showing in particular a significant electromagnetic enhancement of the Raman signal under p-polarized light excitation. TIR-TERS spectra of Cc confirm the 6cLS ferric state assignment deduced from TIR-SERS spectra, thus demonstrating the possibility of probing with nanoscale spatial resolution the 6cLS oxidized form of Cc that is potentially implicated in cell apoptotic processes. The minimal far-field contribution of the sample in TIR-TERS also offers promising perspectives for future nanoscale chemical characterizations of photosensitive biomolecules in complex biological media.Lead halide perovskite (APbX3) nanocrystals exhibit photoluminescence (PL) with both wide wavelength tunability and high quantum efficiency. While the Pb-X6 octahedra mainly determines the near-band-edge optical properties and the A-site cation affects the structural stability, the role of the A-site cation in determining the optical properties is still unclear. Here, we report the PL properties of three types of lead bromide perovskite APbBr3 nanocrystals with different cations [A = HC(NH2)2+, CH3NH3+, and Cs+], as revealed by single-dot spectroscopy, and discuss the influence of the A-site cation on the PL spectrum. The nanocrystal size dependences of the PL energy and lifetime show no large variation with the species of the A-site cation. We find that the size of the A-site cation determines the coupling strength between electrons and longitudinal-optical phonons in the nanocrystal and thus affects the PL spectral shape, especially the low-energy tail.This study aims to investigate the growth of a cation-exchangeable hydrated layer on the surface of mica-type silicates based on a synthetic fluorophlogopite and a natural muscovite. Through the reaction of a synthetic fluorophlogopite using LiF, MgCl2, and a silica sol in water at 373 K for 48 h in the presence of urea, a hydrated phyllosilicate was formed on the fluoromica. As a result of examining the reaction in the alkali solution in the absence of Mg2+, the uptake of the silica sol would be included as a chemical process to begin the crystallization on fluorophlogopite because the lithium and ammonium ions (generated by urea hydrolysis) are known to contribute to enhanced adsorption. We found that the urea hydrolysis increased the pH, which, in turn, assisted the formation of magnesium hydroxide after the isomorphic substitution of Li+ for Mg2+. Bridging tetrahedral SiO4 with a magnesium-lithium double hydroxide afforded a 1 nm silicate layer. This facilitated the hectorite-like hydrated silicate layer to adhere closely to both the crystal edge and the cleaved face of the synthetic mica, which was found to coat the surface homogeneously. Only surface crystals were found to form through this process. 17-DMAG The layered silicates included exchangeable hydrated cations for the cation-exchange reactions to expand the interlayer space by a cationic surfactant, dimethyldistearylammonium. The layered silicate also adsorbed methylene blue as a cationic dye in the aqueous phase. Apart from fluoromica, the natural muscovite also provided the surface to grow hydrated silicate layers, as a crystal turned dense blue when reacted with methylene blue.A method for the synthesis of highly substituted cyclopropanes via a quasi-Favorskii rearrangement is described. The method includes the combination two chemical transformations starting from α,α-dichlorocyclobutanones prepared via the [2 + 2] Staudinger ketene cycloaddition between either terminal- or cis-olefins and dichloroketene. First, α,α-dichlorocyclobutanones are reacted with organocerium reagents to afford the corresponding tertiary alcohols in good to excellent yields through a nucleophilic addition reaction that provided exclusively anti-products. Second, upon irreversible deprotonation, the tertiary α,α-dichlorocyclobutanols underwent a ring-contraction reaction (i.e., quasi-Favorskii rearrangement) to form structurally diverse cyclopropanes in moderate to good yields. The syn-stereoselectivity during the quasi-Favorskii rearrangement was evaluated using DFT analysis.