Supramolecular organization of the crystal structure of <Emphasis Type="Italic">cis</Emphasis>-bis(thiosemicarbazide)palladium(II) <Emphasis Type="Italic">ortho</Emphasis>-hydrophthalate

This paper reports on the synthesis of a new palladium(II) thiosemicarbazide complex of the composition [Pd(HL)₂](HPht)₂ · 4H₂O(I) (where HL is N(1)H₂-N(2)H-C(3)(=S)-N(4)H₂ and HPht ⁻ is a monoanion of ortho-phthalic acid) and the results of an investigation of its structure. It has been demonstrated that two organic ligands are bidentately coordinated in the neutral form through a set of N and S donor atoms, which are located in the cis position with respect to the central metal atom. Three independent water molecules are joined by hydrogen bonds into the centrosymmetric associate {H₂O}₆. In the crystal, thiosemi-carbazide cationic complexes of palladium(II), monophthalate anions, and water molecules are self-organized into a supramolecular system with the formation of a three-dimensional structure based on ionic and hydrogen bonds.     

Synthesis and Size-Selective Application of Palladium Metal Particles Intercalated in Mesopore-Size Controlled Smectite

Abstract

Mesoporous smectite-type materials (SM) were synthesized with a hydrothermal method from water glass, magnesium chloride and alkyl ammonium salt. The mesopore diameter of SM was controlled from 30 to 130 Å by changing the reaction temperature, pH and the template materials during hydrothermal treatment. Palladium metal particles were intercalated in the mesopores of SM with an ion-exchanging of [Pd(NH₃)₄Cl₂] on them and hydrogen reduction treatment. The size-selective hydrogenation of butadiene-acrylonitrile rubbers (NBR) in carbon tetrachloride was studied using palladium loaded smectite catalysts (Pd-SM). The reaction was controlled by the sizes of mesopore of Pd-SM, which determine the diffusion of polymer molecules onto the dispersed palladium particles within the pores.     

Influence of laser treatment on thermodynamic and kinetic parameters of lithium intercalation process into nanosized SiO2

Amorphous nanosized SiO₂ powder has been modified by laser treatment. The influence of this treatment on the structure and parameters of a process of Li⁺ electrochemical intercalation into cathodes based on SiO₂ has been studied by means of an X-ray analysis, infrared spectroscopy, electro-motive force and impedance spectroscopy methods.     

Fiber-optic Fabry-Perot microresonator for near-field optical microscopy systems

The possibility of developing a new type of interferometric near-field aperture probe for near-field optical microscopy using a fiber-optic Fabry-Perot microresonator with a nanosized orifice formed in one of its output mirrors has been studied theoretically and experimentally. It is shown, both theoretically and experimentally, that this method provides a spatial resolution of no worse than λ/30.     

Electro-optical probe for studying local fields in organic heterostructures

Dielectric, optical, and electro-optical properties of thin Langmuir films (40–130 nm thick) of meso-substituted palladium tetraphenylporphyrin have been investigated. The key parameter of the characteristic electro-absorption band of this material—the difference in the polarizability for the excited and ground states of its molecules—has been determined. The example of determining the local field in the polymer ferroelectric in the composition of two-layer heterostructure is shown.     

Hydrogen transport in a machinable glass-ceramic

A commercial, machinable glass-ceramic (CGW-9658) has been found to change color from white to dark grey upon exposure to hydrogen isotopes at temperatures of 500°C and above. This process has been studied by optical microscopy and electron spin resonance as a function of temperature, gas pressure, and hydrogen isotope used. The results demonstrate a one-to-one correspondence between the diffusion-controlled reduction of ferric iron by hydrogen and the visually observed width of the reacted zone.     

Structure and disorder in schultenite,lead hydrogen arsenate

The structure of lead hydrogen arsenate has been studied by pulsed neutron single crystal diffraction. The structural parameters obtained agree well with the best available X-ray data. In addition, the hydrogen atom positions and disorder have been well characterized, yielding potentially important information regarding hydrogen atom potentials.     

Crystal and molecular structure of N-(2-morpholinoethyl)-2-oximato-1-phenylpropan-1-iminechloropalladium(II)

The crystal structure ofN-(2-morpholinoethyl)-2-oximato-1-phenylpropan-1-iminechloropalladium(II), [Pd(L)Cl], has been determined from X-ray data collected by counter methods. The compound crystallizes in the orthorhombic space groupPna2₁ with four molecules per unit cell, the dimensions of which area=9.602(2),b=8.150(1),c=21.181(4) Å. Full matrix least-squares refinement gave a finalR value of 0.042 for the 3218 independent observed reflections. The oxime ligand is deprotonated and is acting as a tridentate ligand coordinating to the palladium through the oxime nitrogen, the imine nitrogen, and the tertiary amine nitrogen of the morpholine moiety. To complete four-coordination about the palladium atom, a chloride ion is also attached to the central metal atom. The donor atoms plus the palladium atom are planar.     

单壁碳纳米管储氢行为的模拟计算研究

利用碳纳米管储氢已经成为了纳米科技领域中的一项研究热点.为了认识碳纳米管的动态储氢过程,本文借助于分子动力学方法,对单壁碳纳米管的储氢行为进行了模拟计算,其结果生动逼真,并得出了储氢的如下结论:被吸附的氢分子主要出现在管内和管外的边缘附近;管内氢分子的分布出现分层现象,且管径越小,则靠近管壁的氢分子分层现象越明显;在管内外靠近管壁处的氢分子与管壁有一定的空隙.这为进一步研究碳纳米管的储氢机理和储氢容量等问题提供了必要的依据.     

Synthesis of Fe-doped nanosized SnO2 powders by chemical co-precipitation method

Fe-doped nanosized SnO₂ powders were prepared by chemical co-precipitation technique using SnCl₄ and FeCl₃ as starting materials and water as a carrier. Experimental results show that the grain size of Fe-doped SnO₂ crystallites is smaller than 5 nm, and the particle size is smaller than 15 nm. When the calcination temperature is below 650 °C, the SnO₂ crystal has tetragonal lattice structure. At higher temperature the particles become a two-phase mixture of tetragonal SnO₂ and hexagonal Fe₂O₃ crystallites. Fe doping can obviously prevent the growth of nanosized SnO₂ crystallites, and a higher Fe-doping concentration is more effective to prevent the growth of nanosized SnO₂ particles when the calcination temperature is below 550 °C.     

System of hydrogen bonds in high-pressure phases of CsHSO4 crystals

The system of hydrogen bonds in the high-pressure phases of CsHSO₄ crystals has been constructed on the basis of the group-theoretical analysis of the systems of hydrogen bonds in the CsHSO₄ phases with the known symmetry.     

Selective growth and other applications of hydrogen-assisted molecular beam epitaxy

The usefulness of atomic hydrogen in molecular beam epitaxy has been demonstrated, centering around selective growth. Atomic hydrogen is effective for low-temperature cleaning of substrates, surfactant effects such as restrain of island growth and suppression of the surface migration of the adatoms and selective growth on masked or V-grooved substrates. These effects are dependent on substrate temperatures. The selective growth of GaAs has been successfully demonstrated at the conventional growth temperature and growth rate with the aid of atomic hydrogen. The main mechanism of the selective growth is the re-evaporation of Ga and As from mask materials such as SiN_x or SiO₂. Selective growth has also been observed on low-index crystal facets. On (111)A and (110) facets, no GaAs was deposited in the presence of atomic hydrogen, the flux of which is approximately the same as that of Ga. GaAs quantum wire structures have been fabricated on the substrates with V-shaped grooves. The efficient capture and confinement of carriers into wire regions have been observed by photolumenescence.     

Hydrogen Adsorption of Alkali Metal Complexes of Polycyclic Aromatic Hydrocarbon and Graphite,and Their Solid State Properties

The hydrogen adsorption in alkali metal complexes of graphite and triphenylene has been investigated by means of ESR and electrical resistivity under hydrogen atmosphere. In the first stage graphite compound C₈Rb, hydrogen molecules are dissociated into atoms which are stabilized in graphite gaps. C⁸K has a two stage hydrogen adsorption process: dissociation and charge transfer. For C₈Cs, the catalytic activity for hydrogen comes from the surface. The second stage compounds C₂₄M (M=K, Rb, and Cs) show weaker activities for hydrogen than the first stage ones. Triphenylene-potassium complex has a two stage process for hydrogen adsorption.     

Method of measuring depth profile of hydrogen in soda-lime glass

The depth profile of hydrogen in glass, as an indicator for the presence of water, has been determined by two independent techniques. Secondary ion mass spectroscopy (SIMS) gives high spatial resolution measurements of the variation of hydrogen concentration as a function of depth into the glass. These measurements are not absolute, however. Elastic recoil detection analysis (ERDA) provides absolute measurements of the variation of hydrogen concentration with depth, although the spatial resolution is only in the order of 50 nm. The combination of the measurements obtained by these two techniques yields absolute high-resolution data of the depth dependence of hydrogen in glass.     

Palladium(II) and platinum(II) tetrakisthiourea dichloride bis(7-hydroxy-5-methyl[1,2,4]triazolo[1,5a]pyrimidine) dihydrate solvates

The title compounds palladium(II) and platinum(II) tetrakisthiourea dichloride bis(7-hydroxy-5-methyl[1,2,4]triazolo[1,5a]pyrimidine (Hmtpo)) dihydrate solvates, have been synthesized by reacting thecis-[MCl₂(Hmtpo)₂] (where M=Pt(II), Pd(II)) complexes with an excess of thiourea (tu) and the structure of the palladium compound was solved by X-ray diffraction. Crystals of [Pd(tu)₄]Cl₂·2Hmtpo·2H₂O are triclinic with space groupP and unit cell dimensionsa=7.972(1),b=9.049(1),c=11.808(2)Å, =88.20(1), =75.15(1), =76.54(1)^o. The cation [Pd(tu)₄]²⁺ is centrosymmetric involving four sulfur thiourea atoms in a near square planar environment. The triazolopyrimidine molecules, chloride anions and water molecules do not take part in the metal center coordination but interact by hydrogen bonding between them and the thiourea moieties. A comparison between powder diffraction data of palladium(II) and platinum(II) compounds clearly indicates that both compounds are isomorphous.     

Structural characteristics and second harmonic generation in l-threonine crystals

l-threonine, an organic material with interesting non-linear optical properties, has been grown in solution and characterized by X-ray diffraction, FT infrared spectral, Raman spectral, UV VIS spectral and thermal techniques. The structural and spectral characteristics show that strong hydrogen bonds appearing in l-threonine have an influence on the stabilization of the crystal structure. The main contributions to the second harmonic generation in threonine results from the hydrogen bond and also from the vibrational part due to very intense IR bands of the hydrogen bond vibrations. The OH and NH involved in strong hydrogen bonds are responsible for the higher thermal stability of l-threonine compared to other organic non-linear optical materials. l-threonine is thermally stable up to 270 °C.     

Self-assembling of detonation nanodiamond and control of the organization in PANI-based nanocomposites: a case study for a tailored shaping of specific 3D architectures

Detonation nanodiamond (DND) is characterized by very attractive properties, as the unusual values of surface energy and confinement effects. The objective of our research is to define methodologies for the tailored shaping of DND aggregates and the control of the architecture in DND-based nanocomposites. Self-standing microstructures with different shapes have been obtained by using different portions of the DND colloidal suspensions. Innovative composites based on DND inserted in PANI matrices are prepared by adding nanodiamond during chemical oxidative polymerization of ANI. The insertion of the nanosized fillers enables to obtain architectures with a high-degree of control over the polymer crystallinity.     

Characteristics of nanosized ruthenium metal by chemical reduction method

Nano-sized Ru metals have been prepared by the chemical reduction of ruthenium chloride and ruthenium hydroxide. Sodium borohydride was used as a reducing agent. The samples have been characterized by elemental analysis, X-ray diffraction, differential scanning calorimetry, and transmission electron microscopy. The preparation method greatly affects the composition and surface area of the material. All the samples show nanosized particles. However, samples prepared by reduction of ruthenium hydroxide had a lower surface area and larger particle size than those prepared by reduction of ruthenium chloride. Residual amount of boron was present in the samples. The samples demonstrate amorphous structure.     

Doping of microcrystalline Si:H,Cl films in R.F. glow discharge

The deposition rate of n-doped μc-Si:H,Cl GD films has been found to increase with the gas phase phosphine content, while the opposite behaviour has been observed for p-doped specimens. The optical gap ranges between 1.8 ÷ 2.6 eV and its variation seems related to hydrogen and chlorine contents. The effectiveness of the doping has been tested by electrical conductivity measurements.     

Charge state and hydrogen diffusion in Ti-based alloys

The electronic structure, charge state, and hydrogen diffusion in icosahedral Ti-based alloys have been investigated by the methods based on the density-functional theory. The charge state of the hydrogen atom in Ti₃₆Zr₃₂Ni₁₃ has been determined for different types of tetrahedral voids. The charge state of hydrogen atoms in Ti₃₆Zr₃₂Ni₁₃, Ti₃₆Hf₃₂Ni₁₃, and Ti₄₈Zr₈Fe₁₈ is calculated for the ratio H/M = 1.7, where H is the number of hydrogen atoms and M is the number of metal atoms. It is established that hydrogen atoms in all objects studied are in an almost neutral state. The hydrogen diffusion coefficient is determined for Ti₃₆Zr₃₂Ni₁₃.