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3R-NbS 2 nanosheets were obtained at high temperature by decomposing of the Nb–HDA complex with H 2 S gas in a N 2 atmosphere. The temperature-dependent electrical resistivity and electrochemical HER activity of 3R-NbS 2 were measured.
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The oscillator strengths of the vibrationally allowed n → π* transitions of acetaldehyde and acetone and their deuterated derivatives are shown to depend mainly on the vibrational frequencies of the mixing modes in the deuterated and undeuterated species. Quantitative agreement is found between the calculated and observed intensity ratios fD/fH.
LaNi1−x Co x O3 shows itinerant d-electron behavior similar to LaNiO3 up to x = 0.5. In the range 0.5 < x < 1.0, the cobalt spin state equilibrium is markedly affected; the localized-itinerant electron transition of LaCoO3 is not seen when x < 0.95. In LaCo1−x Fe x O3, itinerancy of d-electrons decreases with increase in x and the compositions with x > 0.5 are similar to LaFeO3. If x > 0.1, the localized-itinerant electron transition is not seen and the cobalt spin state equilibrium is considerably altered. In LaNi1−x Fe x O3, itinerancy decreases with increase in x. These observations can be satisfactorily explained in terms of Goodenough's energy band schemes.
A careful investigation of the structures and charge densities of the β and α polymorphs of p-nitrophenol has been carried out. Although the two forms crystallize in different monoclinic cells, the crystal densities are similar. There are, however, several differences in the intramolecular structural features of the two forms, including the C−C−O bond angles and the N−O distances. The α form exhibits a large number of intermolecular hydrogen contacts. More importantly, a detailed charge density analysis of the two forms has brought out significant differences in the charge distribution in both the intra- and the intermolecular hydrogen bonding regions. Deformation density maps reveal many differences in the bonding regions of the molecule in the two forms. Charge migration from the benzene ring region of the molecule to the nitro and the hydroxyl groups occurs as the structure changes from the β to the α form. Relief maps of the negative Laplacians in the plane of the intermolecular hydrogen bonds show polarization of the oxygen lone-pair electrons toward hydrogen. The molecular dipole moments in the solid state, derived from the pseudoatomic charges in the β and α structures, are considerably larger (∼20 D) than the value in the free molecule.
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Stabilization of individual 0D metal–organic polyhedra (MOP) on 2D graphene and 1D single-walled carbon nanotube (SWNT) surfaces results in a significant improvement of porosity, surface area and catalytic activity of the composites.
The energy corresponding to the exciplex emission of substituted N,N-dimethylanilines with authracene decreases with increase in the electron donating power of the substituent. The solvent dependence of the exciplex emission band can be explained in terms of the variation in the dimensions of the complex. N,N-Dimethyl-p-nitrosoaniline (DMNA)-aromatic systems exhibit fluorescence similar to DMNA possibly because of the formation of a loose exciplex of the type (DMNA*-aromatic).
Investigations of open-framework zinc phosphates have demonstrated that the formation of the complex 3D architectures may involve a process wherein one-dimensional ladders or chains, and possibly zero-dimensional monomerscomprising four-membered rings transform to the higher dimensional structures. The one-dimensional ladder and the 4-membered rings appear to be important building units of these structures. At one stage of the building-up process, spontaneous self-assembly of a low-dimensional structure such as the ladder could occur, followed by the crystallization of a three-dimensional structure. Accordingly, many of the higher dimensional structures retain structural features of the OD or 1D structure. It is significant that a four-membered ring zinc phosphate has been found recently to spontaneously yield a linear chain phosphate at room temperature, on addition of piperazine, the chain transforming to a sodalite-type 3D structure under mild conditions. The occurrence of a hierarchy of structures from zero- to three-dimensions is found in open-framework metal oxalates as well. Interestingly, the three-dimensional sodalite structure is generated readily by the assembly of metal squarates, possessing the 4-membered ring motif. It is noteworthy that open-framework structures are also formed by oxyanions such as sulphate and selenite.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
The international conference series on Advances in Steel Structures was initiated in 1996, under the auspices of the Hong Kong Polytechnic University, which remained very active in fostering its continuation - joined, a few years later, by the Hong Kong Institute of Steel Construction. The eighth conference of the series, ICASS’2015, took place in Lisbon, Portugal on July 21-24, 2015 - the venue was Instituto Superior Técnico from the University of Lisbon. It was the first conference of the series to take place outside of Asia. Indeed, the first, second, third and sixth conferences were held in Hong Kong, the fourth in Shanghai, the fifth in Singapore and the seventh in Nanjing. As its predecessors, ICASS’2015 aimed at providing a forum for the discussion and dissemination, by both researchers and designers, of the most recent theoretical, numerical and experimental advances in the analysis, behaviour, design and construction of steel, aluminium and composite steel-concrete structures.
Abstract : This infrared bibliography is based on a systematic search of the literature on infrared spectroscopy up to the end of 1960. The literature search has been made by going through journals as well as through Chemical Abstracts. As a general rule, any paper of interest in the field of infrared spectroscopy is included: Examples of fringe areas include microwave spectra where rotational constants are given, papers on preparation of chemical compounds where infrared spectra are used for identification, papers on Beer's law, references to mathematical treatments such as group theory and statistical mechanics and so on. Papers on Raman spectroscopy have, however, not been included. The bibliography has been divided into four sections: I, Organic Compounds; II, Inorganic Compounds (a, of non-metals; b, of metals); III, Polymeric compounds; and IV, Minerals and Ores.
Three-dimensional open-framework metal selenites of the formula, [H2N(CH2)4NH2]0.5[M(HSeO3)(Se2O5)] (M = Zn, Co or Ni), containing both selenite and diselenite units and intersecting 10-membered channels, have been prepared hydrothermally in the presence of piperazine. The compounds are isomorphous and crystallize in the P-1 space group. The structure is built up of MO6 dimers along with Se2O5 and HSeO3 units, the first two forming sheets, which are connected by the selenite units to yield a three-dimensional non-interpenetrating diamondoid network. The 10-membered channels have an unusual structure, being formed by 4-membered (M2Se2) and 6-membered (M2Se4) rings.
Covalent functionalisation of nanodiamond has been carried out by employing several methods. One of them involves the reaction of acid-treated nanodiamond with thionyl chloride followed by reaction with a long-chain aliphatic amine to produce the amide derivative. The second method involves reaction of acid-treated nanodiamond with an organosilicon or organotin reagent such as hexadecyltrimethoxysilane, dibutyldimethoxytin, and perfluoro-octyltriethoxysilane. The products of covalent functionalisation produce excellent dispersions in CCl4 and toluene. SiO2–and SnO2–covered nanodiamond are obtained by heating the nanodiamond coated with the organosilane and the organotin reagents, respectively. By interaction of nanodiamond with surfactants such as sodium bis(2-ethylhexyl) sulphosuccinate (AOT), Triton X-100 (TX-100), polyvinyl alcohol (PVA), cetyltrimethylammonium bromide (CTAB), and tert-octylphenoxy poly(oxyethylene)ethanol (IGEPAL) gives good dispersions in water, the best dispersion with the lowest surfactant concentration being obtained with IGEPAL.
Two inorganic–organic hybrid framework iron phosphate–oxalates, I, [N2C4H12]0.5[Fe2(HPO4)(C2O4)1.5] and II, [Fe2(OH2)PO4(C2O4)0.5], have been synthesized by hydrothermal means and the structures determined by X-ray crystallography. Crystal Data: compound I, monoclinic, spacegroup=P21/c (No. 14), a=7.569(2) Å, b=7.821(2) Å, c=18.033(4) Å, β=98.8(1)°, V=1055.0(4) Å3, Z=4, M=382.8, D calc=2.41 g cm−3, MoKα, R F=0.02; compound II, monoclinic, spacegroup=P21/c (No. 14), a=10.240(1) b=6.375(3) Å, c=9.955(1) Å, β=117.3(1)°, V=577.4(1) Å3, Z=4, M=268.7, D calc=3.09 g cm−3, MoKα, R F=0.03. These materials contain a high proportion of three-coordinated oxygens and [Fe2O9] dimeric units, besides other interesting structural features. The connectivity of Fe2O9 is entirely different in the two materials resulting in the formation of a continuous chain of Fe–O–Fe in II. The phosphate–oxalate containing the amine, I, forms well-defined channels. Magnetic susceptibility measurements show FeII to be in the high-spin state (t 4 2g e 2 g ) in II, and in the intermediate-spin state (t 5 2g e 1 g ) in I.
The Metropolis Monte Carlo method in the isothermal isobaric ensemble has been extended to enable study of phase transitions in molecular systems, and used to investigate the transition from the crystalline to the orientationally disordered (plastic-crystalline) phase of carbon tetrachloride. The problem of rotation of the cell has been examined. The radial distribution functions, displays of the molecular arrangements in the crystal, and the cosine of the angle between the molecular C 3 axis and the crystallographic [101] direction show clear evidence for the existence of a transition around the temperature expected from experiments.
