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General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Matériaux particuliers, Specific materials, Fullerènes et matériaux apparentés; diamants, graphite, Fullerenes and related materials; diamonds, graphite, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Biomasse, Biomass, Biomasa, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Décarbonylation, Decarbonylation, Descarbonilación, Décarboxylation, Decarboxylation, Descarboxilación, Désoxygénation, Deoxygenation, Desoxigenación, Fullerènes, Fullerenes, Modèle, Models, Modelo, Protection environnement, Environmental protection, Protección medio ambiente, Hydrodésoxygénation, Hydrodeoxygenation, Decarbonylation/decarboxylation, Fullerene-like MOS2, Hydrotreatment, Liquefied biomass, and Lumped deoxygenation model

Hydrotreatment of liquefied lignocellulosic biomass was investigated at 300 °C under the total pressure of 8 MPa in a slurry reactor over unsupported molybdenum (disulphide, dioxide and carbide) and tungsten (disulphide) catalysts. Novel nanostructured urchin-like MoS2 and inorganic-fullerene MoS2 interconnected with carbon materials were synthetized and tested, while the influence of metal variation and the sulphide replacement with carbide or oxide was also investigated by using commercially available MoS2, Mo2C, MoO2 and WS2. Catalysts were structurally characterised by field-emission scanning (SEM) and high-resolution transmission (HRTEM) electron microscopies, energy-dispersive X-ray (EDX) and Raman spectroscopies, as well as X-ray diffraction (XRD). The hydrodeoxygenation (HDO), decarbonylation, decarboxylation and hydrocracking kinetics of depolymerised cellulose, hemicellulose and lignin were determined according to the transformation of their functional groups in liquid phase, and the corresponding gaseous products by an innovative lumped kinetic model based on Fourier transform infrared spectroscopy. Unsupported MoS2 catalysts showed high hydrogenolysis selectivity, the morphology clearly affecting its rate. A high HDO activity reflected in the mass balance and phase distribution of the upgraded liquid product by reducing tar residue and increasing the yield of oil phase with the gross calorific value of 38 MJ kg-1 and oxygen content below 8.5 wt%.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Diffusion(transport), Diffusion, Etat adsorbé, Adsorbed state, Estado adsorbido, Microscopie tunnel balayage, Scanning tunneling microscopy, Métal transition, Transition elements, Méthode fonctionnelle densité, Density functional method, Platine, Platinum, Pt, Aromatic adsorbates, Density functional theory, and Van der Waals

We present a combined density functional theory (DFT) and scanning tunneling microscopy (STM) investigation of the adsorption and diffusion of non-interacting 2,2,2-trifluoroacetophenone (TFAP) and (R)-(+)-1-(1-naphthyl)ethylamine ((R)-NEA) on the Pt(111) surface. The two adsorbates are prochiral and chiral, respectively, and their surface diffusion is of specific interest in relation to chirality transfer from chiral modifiers to prochiral reactants in Orito-type hydrogenation on metal catalysts. Using a van der Waals-DFT description, the two adsorbates are shown to bind strongly to the surface through the aromatic groups and their respective side groups with carbonyl and amine functions. Adsorption energies were calculated for twelve different (R)-NEA adsorption conformers. A naming convention is introduced to describe the different conformers, and the two most stable ones are labeled (R)-NEA-1 and (R)-NEA-2. Diffusion of both adsorbates is calculated to proceed in a walking manner, moving either the aromatic group or the substituent group. For TFAP a diffusion barrier of 0.66 eV is calculated while 0.74-0.89 eV barriers are found for the two adsorption conformers of (R)-NEA. In agreement with the computed results, the room temperature STM study shows rapid diffusion of TFAP and significantly slower diffusion of (R)-NEA. Whereas TFAP monomers are rarely imaged at room temperature, consistent with rapid diffusion, time-lapsed images of (R)-NEA show limited molecular motion in localized regions of the surface. Furthermore, the motion of (R)-NEA is strongly conformation dependent. (R)-NEA-1 displays a much greater propensity to undergo rotational motion. The STM data for (R)-NEA are compared with DFT calculated energy barriers for translation and rotation. The possible implications of the experimental and calculated data for a role for induced fit stereodirection by (R)-NEA/Pt(111) are commented on.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Autoassemblage, Self-assembly, Matériau poreux, Porous materials, Modélisation, Modelling, Méthode Monte Carlo, Monte Carlo methods, Simulation numérique, Digital simulation, Surcouche, Overlayers, Adsorption, Chiral porous networks, Functional molecules, and Monte Carlo simulations

Formation of complex ordered patterns by simple molecular building blocks adsorbed on solid substrates is an intriguing phenomenon in which small changes in the geometry and chemistry of the molecular brick can lead to entirely different 2D architectures. In this contribution we demonstrate how theoretical modeling can be effectively used to predict the morphology of adsorbed overlayers comprising cross-shaped functional molecules equipped with active interaction centers. In particular, we use the Monte Carlo lattice model to explore the effect of distribution of the centers within the probe molecule on the structure of the corresponding molecular assemblies. The simulated results show that, depending on the number and position of the active centers, the outcome of the self-assembly can be extended homochiral porous networks, molecular strings and dispersed molecular clusters. Our theoretical investigations can be helpful in custom designing methods for imparting chirality to solid surfaces via the adsorption of functional molecules.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Métal transition, Transition elements, Chiral, Inorganic materials, and Topological insulators

We demonstrate that an intrinsically chiral, high Miller index surface of an achiral metal can be used to template the enantioselective growth of chiral transition metal chalcogenide films. Specifically, Cu(643)R can be used as a template for the enantioselective growth of a chiral copper telluride alloy surface. Beyond a critical alloy thickness the chiral influence of the Cu(643)R surface diminishes and an achiral surface forms. Our work demonstrates a new method of producing chiral transition metal chalcogenide surfaces, with potential applications in the study of structurally chiral topological insulators.

Biochemistry, molecular biology, biophysics, Biochimie, biologie moléculaire, biophysique, General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Rhéologie, Rheology, Techniques et appareillage, Techniques and apparatus, Mesures rhéologiques, Rheological measurements, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Mécanique fluide, Fluid mechanics, Mecánica flúido, Article synthèse, Review, Artículo síntesis, Couche mince, Thin film, Capa fina, Microfluidique, Microfluidics, Microfluidic, Propriété rhéologique, Rheological properties, Propiedad reológica, Rhéologie, Rheology, Reología, Microrhéologie, Microrheology, Microrheometric, Piezo vibrators, Thin film rheology, and Wall slip

Microrheology probes the mesoscale between bulk rheology, which provides an integral sample response, and nanorheology, which refers to a local response at a molecular confinement level. The term 'microrheology' is often used to refer to optical particle tracking methods that measure a local response of a sample. In contrast to this, non-optical microrheology techniques generally allow two different effects to be studied: actual confinement effects on the rheology and boundary effects such as slip. Investigating the mesoscale range has additional advantages such as the possibility to perform measurements with small sample volumes and at high shear rates. This review bundles the wide array of non-optical techniques into five categories: adaptations to a conventional rotational rheometer, sliding plate rheometry on a micrometer scale, microfluidics, piezo vibrators and radial channel flows. The concept of each set of techniques is described, together with their operational window and examples of recent studies.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Chimie surface, Surface chemistry, Cuivre, Copper, Dépendance température, Temperature dependence, EXAFS, Métal transition, Transition elements, Spectrométrie photoélectron, Photoelectron spectroscopy, TDS, Cu, Alanine, Chiral surfaces, NEXAFS, and TPD

Adsorption of L-alanine on the Cu{111} single crystal surface was investigated as a model system for interactions between small chiral modifier molecules and close-packed metal surfaces. Synchrotron-based X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy are used to determine the chemical state, bond coordination and out-of-plane orientation of the molecule on the surface. Alanine adsorbs in its anionic form at room temperature, whilst at low temperature the overlayer consists of anionic and zwitterionic molecules. NEXAFS spectra exhibit a strong angular dependence of the π* resonance associated with the carboxylate group, which allows determining the tilt angle of this group with respect to the surface plane (48° ± 2°) at room temperature. Low-energy electron diffraction (LEED) shows ap (2 √13 x 2 √13) R13° superstructure with only one domain, which breaks the mirror symmetry of the substrate and, thus, induces global chirality to the surface. Temperature-programmed XPS (TP-XPS) and temperature-programmed desorption (TPD) experiments indicate that the zwitterionic form converts into the anionic species (alaninate) at 293 K. The latter desorbs/decomposes between 435 K and 445 K.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Catalyse, Catalysis, Chimisorption, Chemisorption, Chiralité, Chirality, Hydrogénation, Hydrogenation, Microscopie tunnel balayage, Scanning tunneling microscopy, Méthode fonctionnelle densité, Density functional method, Asymmetric hydrogenation, Chiral modifier, Density functional theory, Heterogeneous catalysis, and Prochiral substrate

Linking STM images to atomic positions determined by DFT calculations is an important step in characterizing the intermolecular interactions at play in many surface processes including asymmetric hydrogenation on heterogeneous catalysts. An accelerated data extraction method is used to collect STM information on the geometry of complexes formed between the two substrates, 2,2,2-trifluoroacetophenone (TFAP) and 3,3,3-methyltrifluoropyruvate (MTFP), and the chiral modifier (R)-(+)-1-(-naphthyl)ethylamine ((R)-NEA) on Pt(111). We present new experimental data for complexes formed by MTFP and the (R)-NEA-1 conformer along with a new and enlarged set of reformulated STM data that extends what was reported in previously published studies of complexed MTFP and TFAP. Atomic geometries based on DFT calculations using PBE, M06-L, and optB88-vdW exchange-correlation functionals will also be presented. It will be shown that both substrates have well-defined complexation geometries when interacting with the modifier and that the relative complexation energies are not markedly sensitive to the functional employed.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Spectre IR, Infrared spectra, Spectre absorption, Absorption spectra, Spectre réflexion, Reflection spectrum, Espectro reflexión, Spectrométrie réflexion, Reflection spectroscopy, TDS, Chiral modification, D-( — )-tartaric acid, Pd(111), Reflection-absorption infrared spectroscopy, and Temperature-programmed desorption

The adsorption of chiral D-( — )-tartaric acid is studied on a Pd(111) substrate using a combination of temperature-programmed desorption (TPD) and reflection-absorption infrared spectroscopy (RAIRS). It is found that reaction at room temperature occurs predominantly via deprotonation of the carboxylic acid groups. Bitartrate species form at ~300 K at low coverages while monotartrate species predominate at higher coverages since the removal of the second proton is inhibited by surface crowding. It also appears that the bitartrate can rehydrogenate on heating to reform some monotartrate species. The hydrogens deriving from the carboxylate group desorbs at ~315 K, and the mono- and bitartrate species are stable to ~390 K where they decompose to evolve hydrogen, carbon dioxide and some water. Carbon monoxide is also formed and evolves in a desorption-rate limited state at ~450 K. Biacidic, second-layer D-( — )-tartaric acid adsorbs at higher coverages and initially desorbs in a state at ~329 K shifting to higher temperatures as the second-layer coverage increases, indicative of attractive interactions between adsorbates. A decomposition intermediate is detected by dosing D-( —)-tartaric acid at Iow temperatures (~100 K) and heating to ~300 K or by dosing at ~300 K and heating to ~320 K. and is characterized by modes at ~1313, 1261, 1202 and 1116 cm-1 assigned to δCH modes and a νalcCO vibration suggesting that the intermediate may form by the removal of the - COO group.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Enantiosélectivité, Enantioselectivity, Enantioselectividad, Nanoparticule, Nanoparticles, Rotation polarisation optique, Optical rotation, Adsorption, Chiral, and Propylene oxide

Au nanoparticles modified with enantiomerically pure D- or L-cysteine have been shown to serve as enantioselective adsorbents of R- and S-propylene oxide. A simple adsorption model and accompanying experimental protocol have been developed to enable optical rotation measurements to be analyzed for quantitative determination of the ratios of the enantiospecific adsorption equilibrium constants of chiral species on the surfaces of chiral nanoparticles, KSL/KSD = KRD/KRL. This analysis is robust in the sense that it obviates the need to measure the absolute surface area of the absorbent nanoparticles, a quantity that is somewhat difficult to obtain accurately. This analysis has been applied to optical rotation data obtained from solutions of R- and S-propylene oxide, in varying concentration ratios, with D- and L-cysteine coated Au nanoparticles, in varying concentration ratios.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Chiralité, Chirality, Alaninol, Amino alcohols, Butanolamine, Chirality measure, Cu(100), and Ethanolamine

Chiral self-assembled molecular networks (SAMNs) are important for technological and fundamental reasons. In spite of the large number of works in this field, the mechanism of chirality transfer from single molecules to large-scale two-dimensional (2D) networks is not fully understood yet. This work reports on the self-assembly of simple amino alcohols with different chirality measures on Cu(100). Ethanolamine (2-amino-1-ethanol), alaninol (2-amino-1-propanol) and butanolamine (2-amino-1-butanol) adsorbed on Cu(100) have been investigated with scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), photoelectron spectroscopy (PES) and density functional theory (DFT) calculations. This study addresses the role of the single-molecule handedness in the global chirality expression, showing how the chirality measure of the precursors plays an important role in the formation of globally chiral superstructures.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Autoorganisation, Self organization, Autoorganización, Chiralité, Chirality, LEED, Microscopie tunnel balayage, Scanning tunneling microscopy, Alanine, Glycine, STM, Self-organization, and Surface chirality

We have compared the behaviour of enantiopure alanine, racemic alanine and glycine on Cu{311} surfaces, using LEED and STM to elucidate the self-organisation. In most respects, similar behaviour is seen in all three cases. At 0.33 ML, an overlayer with (2,1;1,2) periodicity is seen: the symmetric lattice (SL) phase. The adsorbate, in anionic form (alaninate or glycinate), adopts a 3-point (μ3) bonding configuration. At higher coverages, networks of boundaries emerge whose orientations break the substrate mirror symmetry. The boundary structure is locally chiral. This chiral lattice (CL) phase involves mixed 2-point (μ2) and μ3 bonding. The CL phase reverts to the SL phase on annealing above 430-440 K. That glycinate forms chiral boundaries demonstrates that boundary chirality can occur without molecular chirality. Glycinate boundaries are very short (10-20 A), and occur in both enantiomeric forms. Enantiopure alaninate boundaries are much longer (several hundred Å), occurring exclusively in one enantiomeric form which is tied to the molecular enantiomer used. Racemic alaninate overlayers exhibit L-alaninate-like domains alternating with D-alaninate-like domains over a length scale of the order of 100 Å. The principal influence of the methyl group, where present, is therefore on which boundary enantiomer occurs, and on the boundary lengths.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Catalyse, Catalysis, Hydrogénation, Hydrogenation, In situ, Nanoparticule, Nanoparticles, Nickel, Ni, Chiral modifier, Enantioselective hydrogenation, Heterogeneous catalysis, and STXM

Enantioselective heterogeneous hydrogenation of C=O bonds is of great potential importance in the synthesis of chirally pure products for the pharmaceutical and fine chemical industries. One of the most widely studied examples of such a reaction is the hydrogenation of β-ketoesters and β-diketoesters over Ni-based catalysts in the presence of a chiral modifier. Here we use scanning transmission X-ray microscopy combined with near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS) to investigate the adsorption of the chiral modifier, namely (R,R)-tartaric acid, onto individual nickel nanoparticles. The C K-edge spectra strongly suggest that tartaric acid deposited onto the nanoparticle surfaces from aqueous solutions undergoes a keto-enol tautomerisation. Furthermore, we are able to interrogate the Ni L2,3-edge resonances of individual metal nanoparticles which, combined with X-ray diffraction (XRD) patterns showed them to consist of a pure nickel phase rather than the more thermodynamically stable bulk nickel oxide. Importantly, there appears to be no particle size effect on the adsorption mode of the tartaric acid in the particle size range ~90-~300 nm.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Enantiosélectivité, Enantioselectivity, Enantioselectividad, Amphibole, Chiral selection, Chiral surfaces, and Pyroxene

Experimental studies of enantioselective molecular adsorption on chiral crystalline surfaces have been limited by the availability of crystals with chiral surfaces of sufficient aerial extent. I propose a simple experimental approach to quantifying enantiomeric excess—a technique that is applicable to any crystal that displays predominantly chiral cleavage faces when crushed, such as the (110) and (1-10) faces of common rock-forming clinopyroxene and clinoamphibole mineral groups. Enantiomeric excesses can be determined by comparing batch adsorption experiments that employ a racemic solution of the adsorbed molecule to similar experiments using pure D or L solutions of the molecular adsorbate.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Cinétique, Kinetics, Composé chiral, Chiral compound, Compuesto quiral, Enantiosélectivité, Enantioselectivity, Enantioselectividad, Métal transition, Transition elements, Platine, Platinum, Spectre IR, Infrared spectra, Spectre absorption, Absorption spectra, TDS, Pt, Infrared absorption spectroscopy, Naphthylethylamine, Propylene oxide, and Temperature programmed desorption

The adsorption of two different chiral molecules on platinum surfaces has been explored as a function of enantiomeric composition. In the first case, the saturation monolayers obtained by the adsorption of 1-(naphthyl) ethylamine (NEA) from CCl4 solutions were characterized in situ by reflection-absorption infrared spectroscopy (RAIRS). It was found that racemic mixtures yield different IR spectra than those obtained from enantiopure monolayers, a behavior that was interpreted as the result of the formation of racemate pairs via hydrogen bonding at the amine moiety also responsible for bonding to the surface. NEA adsorption under these conditions is reversible and can be modified by subsequent exposures to solutions of different chiral compositions, but that appears to take place only via changes in the relative fractions of enantiopure versus racemic domains on the surface; no other enantiomeric ratios are apparent in the IR data. The second study focused on the uptake of propylene oxide (PO) on Pt(111) under ultrahigh vacuum (UHV) conditions. In that case, racemic monolayers show densities up to ~20% lower than those obtained with one single enantiomer. This can be explained by kinetic arguments, since data from isothermal molecular-beam experiments indicated that the PO sticking coefficient depends on the chirality of the incoming PO molecules relative to that of the neighboring adsorbed PO species. Monte Carlo simulations could reproduce the experimental data by assuming adsorbate-assisted adsorption and enantiospecific adsorption geometries for molecules impinging on sites adjacent to previously adsorbed surface species.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Méthode fonctionnelle densité, Density functional method, Physisorption, Fisisorción, TDS, Density functional theory, and Temperature programmed desorption

The physisorption of R-3-methylcyclohexanone on low and high Miller index Cu surfaces is studied with temperature programmed desorption (TPD) and density functional theory (DFT). The DFT calculations are performed with D2, vdW-optB86b, and vdW-optB88 dispersion corrected methods. The adsorption energies calculated by the dispersion corrected methods are more comparable to the TPD results than those calculated without dispersion corrections, although, the former methods have a tendency to overbind the surface adsorbates. The implementation of dispersion corrected methods also indicates a possible adsorbate induced surface reconstruction on Cu(110).

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Autoassemblage, Self-assembly, Chimie surface, Surface chemistry, Chiralité, Chirality, Microscopie tunnel balayage, Scanning tunneling microscopy, Méthode fonctionnelle densité, Density functional method, Density functional theory, and Ferroelectrics

The self-assembly of 3-hydroxyphenalenone (3-HPLN) on the Ag(111) surface has been studied with scanning tunneling microscopy and first-principles computations. The prochiral 3-HPLN molecule forms zipper-like chains when deposited on the Ag(111) surface, representing a 2D analog of their arrangement in bulk crystals. Upon annealing, local chiral trimer motifs form and serve as building blocks in extended 2D supramolecular networks not observed in 3D crystals. The extended network is porous and is held together via weak van der Waals interactions. The dispersion forces between trimers suggest that their handedness is overall racemic, but the asymmetric packing of 3-HPLN trimers around the pores leads to a chiral network. The offset alignment of neighboring 3-HPLN molecules in the unit cell resembles the offset between neighboring particles that are seen in the most efficient packings of rounded triangles. Computations illustrate that charge is transferred from the Ag(111) surface to the lowest unoccupied orbital of 3-HPLN, and a number of networks (including a honeycomb, as well as an alternative close-packed arrangement) are investigated.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Chiralité, Chirality, Microscopie tunnel balayage, Scanning tunneling microscopy, Méthode fonctionnelle densité, Density functional method, DFT, Fumaric acid, Reconstruction, and STM

The interaction of fumaric acid with the Cut (110) has been investigated in UHV by means of low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), reflection absorption infrared spectroscopy (RAIRS), temperature programmed desorption (TPD), scanning tunneling microscopy (STM) and density functional theory (DFT). Different long-range ordered structures appear in LEED after gently annealing. It is found that rows consisting of metal adatoms are strung along the < 1, ± 1 > directions, thus breaking locally the mirror symmetry of the surface. Models proposed by DFT are in good agreement with the STM appearance.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Autoassemblage, Self-assembly, Amino acid, Au(111), Chiral self-assembly, Cysteine adsorption, Homocysteine, and Methionine

A combined classical/quantum methodology is used to examine chiral effects upon adsorption of three sulfur-containing amino acids on the Au(111) surface: cysteine, homocysteine and methionine. Parallel tempering Monte Carlo simulations were employed to broadly examine the configurational space of monomers, dimers and trimers of the molecules on the gold surface. Density functional theory was applied to promising structural targets in order to incorporate higher order electronic structure effects in a study of relative stabilities of the various molecular states upon adsorption. As the precursors of chiral structure formation, like and unlike dimers were investigated at some length, with consideration given to the mode of sorption (chemisorption of physisorption) and the existence of zwitterionic states. We found that neutral (non-zwitterionic) molecules adsorbed weakly on the highly-coordinated Au(111) surfaces. As a consequence, pair configurations in dimers were insufficiently constrained to lead to differential stabilities of homochiral and heterochiral dimers. Whereas neutral molecule interactions were non-discriminating, strong chiral discrimination was found in zwitterionic amino acids. The zwitterionic forms of the larger molecules equilibrated closer to the surface, and the stronger molecule-molecule and molecule-surface interactions were such that homochiral dimers were stable whereas heterochiral dimers were not.