Native and graphene-coated flat and stepped surfaces of TiC

Titanium carbide attracts growing interest as a substrate for graphene growth and as a component of the composite carbon materials for supercapacitors, an electrode material for metal-air batteries. For all these applications, the surface chemistry of titanium carbide is highly relevant and being, however, insufficiently explored especially at atomic level is a subject of our studies. Applying X-ray photoelectron spectroscopy (XPS) to clean (111) and (755) surfaces of TiC, we were able to obtain the detailed spectroscopic pattern containing information on the plasmon structure, shake up satellite, the peak asymmetry and, finally, surface core level shift (SCLS) in C 1s spectra. The latter is essential for further precise studies of chemical reactions. Later on, we studied interface between TiC (111) and (755) and graphene and found the SCLS variation due to strong chemical interaction between graphene and substrate. This interaction is also reflected in the peculiar band structure of graphene probed by angle-resolved photoelectron spectroscopy (ARPES). Based on LEED data the structure is close to (7√3 × 7√3)R30°, with graphene being slightly corrugated. We found that similarly to the graphene on metals, the chemical interaction between graphene and TiC can be weakened by means of intercalation of oxygen atoms underneath graphene.We thank Helmholtz-Zentrum Berlin (HZB) for the allocation of synchrotron radiation beamtimes at the Russian-German and UE112-PGM2 beamlines. The work was financially supported by the Russian Science Foundation (project 16-42-01093). DFT calculations were performed at “Lomonosov” MSU supercomputer.Peer reviewe

High pressure promoted aza-Michael addition of primary and secondary amines to α-substituted acrylates

International audienc

Regioselectivity of the Conjugate Addition of Amines to Dissymmetrical Pull‐Pull Alkenes

International audienceThe regioselectivity of the conjugate nucleophilic addition of amines to vicinal di-acceptor-substituted alkenes has been studied. A set of results obtained with standard primary and secondary amines gives some clues on the relative acceptor character of classical electron-withdrawing groups (EWG). We have shown in addition that computed inverse local nucleophilicity index can be used to predict the regioselectivity of the nucleophilic attack

Solvent effects in the aza-Michael addition of anilines

International audienceThe aza-Michael addition of functionally substituted anilines to enoates is significantly affected by the hydrogen bond donor ability of the solvent. Very polar protic fluorinated alcohols (hexafluoroisopropanol and trifluoroethanol) favor the addition of weak nucleophiles, whereas these solvents are no longer required for anilines bearing additional OH or NH2 group.L'adition d'aza-Michael d'anilines fonctionnalisées sur des énoates est profondément influencée par le pouvoir donneur des liaisons hydrogène du solvant. Les alcools fluorés protiques polaires (HFIP et TFE) favorisent l'addition de ces nucléophiles faibles, alors que leur utilisation n'est pas requise avec des anilines porteuses de groupements OH (hydroxyaniline) ou NH2 (phénylènediamine)

Adamantyl aziridines via aza-Michael initiated ring closure (aza-MIRC) reaction

International audienceAn efficient one-pot synthesis of functionalized adamantylaziridines by aza-Michael initiated ring closure (aza-MIRC) reaction of 1-aminoadamantane with α-halogenated Michael acceptors is described. The reaction goes through an aza-Michael intermediate that undergoes an intramolecular nucleophilic substitution. Expectedly, high pressure exerts a beneficial influence in the case of sterically hindered reagents

Alkyl-and arylsulfanyl-substituted unsaturated carbonyl compounds

<p>A method for the synthesis of captodative sulfanyl enals, enones and enoates <i>via</i> nucleophilic vinylic substitution of corresponding halogen-bearing derivatives has been developed. The <i>one-pot</i> treatment of the haloenoates, haloenones or haloenals with thiols in the presence of organic base leads either to vicinal dithiosubstituted carbonyl-bearing compound or captodative systems with good to excellent yield. The major reaction direction strongly depends on the type of base used.</p

Benefits of a Dual Chemical and Physical Activation: Direct aza-Michael Addition of Anilines Promoted by Solvent Effect under High Pressure

The unique combination of hexafluoroisopropanol (HFIP) employed as solvent and hyperbaric conditions (10–15 kbar) allows unprecedented 1,4-addition of poor nucleophiles, such as aromatic amines, onto sluggish (cumbersome) Michael acceptors without any promoter or workup