Differentiation among some isomeric di- and trifunctional aromatic amines by plasma desorption mass spectrometry

Isomeric di- and trifunctional aromatic amines are easily differentiated on the basis of their plasma desorption (PD) mass spectra. Six series of aromatic amines were studied in the positive-ion mode. In each series, the differences observed in the PD mass spectra allow each isomer to be characterized. In the formation of molecular ions, these differences proceed from the competition between electron impact ionization and protonation. Several chemoselective or regioselective reactions such as hydrogenation, hydration, dimerization and some fragmentations also allow isomeric aromatic amines to be differentiated.     

Exploiting C3-symmetry in the dynamic coordination of a chiral trisoxazoline to copper(II): improved enantioselectivity, and catalyst stability in asymmetric lewis acid catalysis

Chiral C3-symmetric trisoxazolines are highly efficient stereodirecting ligands in enantioselective Cu(II) Lewis acid catalysis which is based on the concept of a stereoelectronic hemilability of the divalent copper; in direct comparison with the analogous bisoxazoline systems they are more efficient in the enantioselective alpha-amination as well as the enantioselective Mannich reaction of prochiral beta-ketoesters.     

Step-controlled synthesis of platinum(II) acetylide frameworks from conjugated polyaromatic modules

A simple synthetic route for the efficient preparation of mono- and dinuclear platinum(II) derivatives containing σ-bonded ethynyl aryl groups is described. A dinuclear complex pointing its two Pt-Cl dipoles in opposite directions is prepared either by complexation of a back-to-back terpyridine ligand with platinum salts or by cross-coupling [(4′-ethynylterpyridine)PtCl] with dibromodidodecylphenyl derivatives. FT-IR, UV-vis absorption and cyclic voltammetry are used as spectroscopic tools to characterize these new complexes.     

On the early stage of aluminum oxidation: An extraction mechanism via oxygen cooperation

We propose a barrierless mechanism for describing the oxidation of Al(111) in which oxygen atoms located on the outer surface extract aluminum atoms of the surface layers through local cooperation of other pre-adsorbed oxygen atoms. We show the details of this complex chemical process that kinetically competes with the non-destructive formation of an oxygen monolayer onto the Al surface, thus elucidating the initial aluminum oxidation regime. We demonstrate that further stripping of the complete surface Al layer is consistent with both (i) the formation of a defective alumina structure and (ii) an oxide capping layer preventing further oxidation at low temperature.     

FTIR investigation of the O-H[middle dot][middle dot][middle dot]Xe interaction in simple carboxylic acids in solid xenon

The O-H stretching region of the infrared spectra of a series of carboxylic acids in Xe matrices was investigated as a function of temperature. Upon increasing the temperature, the νO-H band site-components undergo reversible frequency blue-shifts, which are larger for the lowest-frequency components. This unprecedented observation indicates both that different types of O-H[middle dot][middle dot][middle dot]Xe specific interactions occur, depending on different trapping sites, and the prevalence of stronger interactions of this type for molecules trapped in sites corresponding to lower frequency νO-H band site-components. These results are in agreement with previous investigations pointing to an increased stabilization and larger νO-H frequency red-shifts in carboxylic acid∕Xe complexes bearing a specific H-bond like O-H[middle dot][middle dot][middle dot]Xe interaction. O-H[middle dot][middle dot][middle dot]Xe interaction energies were obtained theoretically and also estimated from the spectroscopic data. Changes in the interaction energies upon temperature variation were also evaluated.     

Internal surface effects in superlattices in contact with substrate

Using the direct matching procedure and the interface response theory, the effects of the internal surface of a superlattice (i.e., the substrate/superlattice interface) are studied as a function of superlattice parameters while the substrate parameters are kept constant. Surface states are found inside mini-gaps and their localization properties are investigated. The crossings of these states with mini-bands are observed and examined by means of the variational density of states.     

Inner mechanics of three-dimensional black holes

We investigate properties of the inner horizons of certain black holes in higher-derivative three-dimensional gravity theories. We focus on Ba?ados-Teitelboim-Zanelli and spacelike warped anti-de Sitter black holes, as well as on asymptotically warped de Sitter solutions exhibiting both a cosmological and a black hole horizon. We verify that a first law is satisfied at the inner horizon, in agreement with the proposal of Castro and Rodriguez [arXiv:1204.1284]. We then show that, in topologically massive gravity, the product of the areas of the inner and outer horizons fails to be independent on the mass, and we trace this to the diffeomorphism anomaly of the theory.