NMR Spectroscopic Signatures of Cationic Surface Sites from Supported Coinage Metals Interacting with N-Heterocyclic Carbenes.

N-heterocyclic carbenes (NHCs) have been extensively studied to modulate the reactivity of molecular catalysts, colloids, and their supported analogues, being isolated sites, clusters, or nanoparticles. While the interaction of NHCs on metal surfaces has been discussed in great detail, showing specific coordination chemistry depending on the type of NHC ligands, much less is known when the metal is dispersed on oxide supports, as in heterogeneous catalysts. Herein, we study the interaction of NHC ligands with Au surface sites dispersed on silica, a nonreducible oxide support.

Isomerization of Aziridines to Allyl Amines via Titanium and Chromium Cooperative Catalysis.

A Ti/Cr cooperative catalyst isomerizes aziridines to allyl amines under mild conditions. The reaction tolerates a broad range of aziridines with various nitrogen substituents. The titanium catalyst is most successful in opening 1,2-disubstituted aziridines, forming radical intermediates in a highly regioselective manner.

Direct and Indirect Electron Transfer Routes of Chromium(VI) Reduction with Different Crystalline Ferric Oxyhydroxides in the Presence of Pyrogenic Carbon.

Electron transfer mediated by iron minerals is considered as a critical redox step for the dynamics of pollutants in soil. Herein, we explored the reduction process of Cr(VI) with different crystalline ferric oxyhydroxides in the presence of pyrogenic carbon (biochar). Both low- and high-crystallinity ferric oxyhydroxides induced Cr(VI) immobilization mainly the sorption process, with a limited reduction process.

Evolution of redox activity of biochar during interaction with soil minerals: Effect on the electron donating and mediating capacities for Cr(VI) reduction.

Biochar in soil is susceptible to natural aging along with soil minerals, which might alter its electrochemical properties and redox reactions with contaminants. In this study, soluble mineral salts (FeCl, MnCl, AlCl, CaCl) and clay mineral (kaolinite) were selected to investigate the impact of co-aging with soil minerals on the redox activity of peanut-shell biochar for Cr(VI) reduction. Natural aging for 3-month induced oxidation of biochar with the decrease of reducing moieties, i.

H· Transfer-Initiated Synthesis of -Lactams: Interpretation of Cycloisomerization and Hydrogenation Ratios.

A cobaloxime/H system used to synthesize valuable -lactams from acrylamide molecules is described. In addition to cycloisomerized lactams, linear hydrogenated products were also observed. The amounts of the hydrogenation product were observed to correlate with the bulk of the substituent on the acrylamide nitrogen.

Catalyzing the Hydrodefluorination of CF-Substituted Alkenes by PhSiH. H• Transfer from a Nickel Hydride.

The hydrodefluorination of CF-substituted alkenes can be catalyzed by a nickel(II) hydride bearing a pincer ligand. The catalyst loading can be as low as 1 mol%. -Difluoroalkenes containing a number of functional groups can be formed in good to excellent yields by a radical mechanism initiated by H• transfer from the nickel hydride.

Interaction with low molecular weight organic acids affects the electron shuttling of biochar for Cr(VI) reduction.

Biochar can act as "electron shuttle" in soil redox reactions. It is possible that biochar accepts the electrons from low molecular weight organic acids (LMWOAs) in soil and then transfer them to the acceptors, e.g.

Anti-Markovnikov alcohols via epoxide hydrogenation through cooperative catalysis.

The opening of epoxides typically requires electrophilic activation, and subsequent nucleophilic (S2) attack on the less substituted carbon leads to alcohols with Markovnikov regioselectivity. We describe a cooperative catalysis approach to anti-Markovnikov alcohols by combining titanocene-catalyzed epoxide opening with chromium-catalyzed hydrogen activation and radical reduction. The titanocene enforces the anti-Markovnikov regioselectivity by forming the more highly substituted radical.

Small Molecule and Peptide Recognition of Protein Transmembrane Domains.

Membrane proteins play vital roles in cell signaling, molecular transportation, and cell adhesion. The interactions of transmembrane domains are much less well understood than those of their water-soluble counterparts, and they have been deemed "undruggable" despite their important biological functions such as protein anchoring, signal transduction, and ligand recognition. Nevertheless, continual developments in this area have revealed useful probes for investigating and regulating these membrane proteins.

Pyrimidine Triazole Thioether Derivatives as Toll-Like Receptor 5 (TLR5)/Flagellin Complex Inhibitors.

Protein-protein interactions have been regarded as "undruggable" despite their importance in many biological processes. The complex formed between host toll-like receptor 5 (TLR5) and flagellin, a globular protein that is the main component of a bacterial flagellum, plays a vital role in a number of pathogen defenses, immunological diseases and cancers. Through high-throughput screening, we identified two hits with a common pharmacophore, which were used to successfully develop a series of small-molecule probes as novel inhibitors of flagellin binding to TLR5.