Search results for "hydrogen"
showing 10 items of 4254 documents
Crystal structure ofp-toluenesulfonylmethyl isocyanide
2015
The molecule of the commercially available title compound, C9H9NO2S, has crystallographically imposed mirror symmetry, the mirror plane passing through the isocyanide group and thepara-C atoms, the methyl C atom and the S atom of the methyl 4-tolyl sulfone moiety. In the crystal, C—H...O hydrogen-bond interactions link the molecules into chains running parallel to thebaxis.
Research frontiers in energy-related materials and applications for 2020-2030
2020
Abstract: This article delineates the state of the art for several materials used in the harvest, conversion, and storage of energy, and analyzes the challenges to be overcome in the decade ahead for them to reach the market and benefit society. The materials covered have had a special interest in recent years and include perovskites, materials for batteries and supercapacitors, graphene, and materials for hydrogen production and storage. Looking at the common challenges for these different systems, scientists in basic research should carefully consider commercial requirements when designing new materials. These include cost and ease of synthesis, abundance of precursors, recyclability of s…
Conventional superconductivity at 203 kelvin at high pressures in the sulfur hydride system.
2015
A superconductor is a material that can conduct electricity without resistance below a superconducting transition temperature, Tc. The highest Tc that has been achieved to date is in the copper oxide system: 133 kelvin at ambient pressure and 164 kelvin at high pressures. As the nature of superconductivity in these materials is still not fully understood (they are not conventional superconductors), the prospects for achieving still higher transition temperatures by this route are not clear. In contrast, the Bardeen-Cooper-Schrieffer theory of conventional superconductivity gives a guide for achieving high Tc with no theoretical upper bound--all that is needed is a favourable combination of …
Prediction of pressure-induced superconductivity in the novel ternary system ScCaH2n (n = 1–6)
2021
Hydrogen-rich systems are currently thought to constitute the most promising potential high-temperature superconductor materials. Here, the high-pressure structure and superconductivity of the ternary hydrogen-rich system ScCaH2n (n = 1–6) are systematically investigated by using the prediction method of particle swarm optimization structure combined with first-principles calculations. As n increases, the electron local function (ELF) indicates that the hydrogen atoms in this system exhibit different behaviors corresponding to single H atoms, H2 molecules, graphene-like layers and, ultimately, H clathrate cages. The electron phonon coupling (EPC) calculation shows that the superconducting t…
Baeyer–Villiger oxidation of ketones with a silica-supported peracid in supercritical carbon dioxide under flow conditions
2009
[2-Percarboxyethyl]-functionalized silica reacts with ketones in supercritical carbon dioxide at 250 bar and 40 °C under flow conditions to yield the corresponding esters and lactones. The solid reagent can be easily recycled through treatment with 70% hydrogen peroxide in the presence of an acid at 0 °C. This procedure not only simplifies the isolation of the reaction products, but has the advantage of using only water and carbon dioxide as solvents under mild conditions.
Organic nanosheets with charged surface: two dimensional self-assembly of a non-symmetric bis-acylurea with pyridyl end group
2011
We present a novel non-symmetric bis-acylurea that self-assembles into two dimensional nanosheet superstructures. The bis-acylurea (PyrC8Bn) has a pyridyl and a benzyl end group divided by a spacer group [–NHCONHCO–(CH2)8–CONHCONH–, C8] with two hydrogen bonding sites. Upon cooling a hot solution in ethanol, the molecule self-assembles into multilayered nanosheet structures due to the intermolecular biaxial hydrogen bonding. The surface charge of the nanosheets could be switched between positive and neutral by adjusting the pH. The charged character of the nanosheets was utilized in immobilizing negatively charged gold nanoparticles. An attempt to regulate the self-assembly allowed us to fi…
Influence of theZ/EIsomerism on the Pathway Complexity of a Squaramide‐Based Macrocycle
2020
The rising interest on pathway complexity in supramolecular polymerization has prompted the finding of novel monomer designs able to stabilize kinetically trapped species and generate supramolecular polymorphs. In the present work, the exploitation of the Z/E (geometrical) isomerism of squaramide (SQ) units to produce various self-assembled isoforms and complex supramolecular polymerization pathways in methylcyclohexane/CHCl3 mixtures is reported for the first time. This is achieved by using a new bissquaramidic macrocycle (MSq) that self-assembles into two markedly different thermodynamic aggregates, AggA (discrete cyclic structures) and AggB (fibrillar structures), depending on the solven…
Synthesis, UV/vis, FT-IR and Mössbauer spectroscopic characterization and molecular structure of the Bis[4-(2-aminoethyl)morpholine](tetrakis(4-metox…
2016
International audience; The synthesis, the UV-visible, FT-IR and Mossbauer spectroscopy and the crystal structure characterizations of the bis[4-(2-Aminoethyl)morpholine]tetrakis(4-metoxyphenyl)porphy-rinato)iron(II) complex are described. The title compound crystallizes in the triclinic, space group P-1, with a = 11.1253(4) angstrom, b = 11.2379(4) angstrom, c = 11.5488(4) angstrom, alpha = 72.304(2)degrees, beta = 86.002(2)degrees gamma = 72.066(2)degrees, V = 1308.28(8) angstrom(3), Z = 1. The Mossbauer data are consistent with an iron(II) low-spin (S = 0) porphyin species. The spin-state is confirmed by the value of the average equatorial iron-nitrogen pyrrole distance (Fe-Np = 1.988(2)…
Geminal Imidazolium Salts: A new Class of Gelators
2012
The gelling behavior of some geminal diimidazolium salts was investigated in solvents differing in polarity and hydrogen bond donor ability. The used salts, namely the 3,3'-di-n-decyl-1,1'(1,4-phenylenedimethylene)diimidazolium dibromide [p-Xyl-(decim)(2)][Br](2) (1), the 3,3'-di-n-dodecyl-1,1'(1,4-phenylenedimethylene)diimidazolium dibromide [p-Xyl-(dodecim)(2)][Br](2) (2), and the 3,3'-di-n-dodecyl-1,1'(1,4-phenylenedimethylene)diimidazolium ditetrafluoroborate [p-Xyl-(dodecim)(2)][BF(4)](2) (3), differ in the alkyl chain length and in the anion properties, such as size, shape, and coordination ability. In all cases in which gelation process was observed, the obtained gels were characteri…
Toward a density functional description of liquid pH2.
2010
A finite-temperature density functional approach to describe the properties of parahydrogen in the liquid-vapor coexistence region is presented. The first proposed functional is zero-range, where the density-gradient term is adjusted so as to reproduce the surface tension of the liquid-vapor interface at low temperature. The second functional is finite-range and, while it is fitted to reproduce bulk pH2 properties only, it is shown to yield surface properties in good agreement with experiments. These functionals are used to study the surface thickness of the liquid-vapor interface, the wetting transition of parahydrogen on a planar Rb model surface, and homogeneous cavitation in bulk liquid…