Materials Literature
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Light-induced reactions of Si surfaces with carboxylic acids to generate Si ester-modified surfaces are studied. The reaction proceeds by photoelectrochemical oxidation of porous or (100)-oriented single-crystal n-type Si in formic, acetic, or trifluoroacetic acid electrolyte solutions. The reaction products at the po…
The details of solution structure have proven difficult to probe experimentally, but computer simulations allow solvent structuring to be examined directly. We report here molecular dynamics (MD) simulations of a series of pentose sugars in solution, describe in detail the three-dimensional structuring which these mol…
A detailed analysis of the Raman spectrum of syndiotactic polystyrene, sPS, in the region 600−850 cm -1 has been undertaken. As sPS exhibits considerable polymorphism, spectra of various preparations including melt-crystallized sPS (α/β form), solvent-crystallized sPS (γ/δ forms), and quenched glassy material were stu…
A mechanism for growth on the diamond (110) surface, with dicarbon (C 2 ) as the growth species, is examined. Reaction energies and activation energies of the various steps in the mechanism were investigated on model systems using molecular quantum mechanics, including the AM1 semiempirical method and the BLYP/6-31G*…
We present a new scaling approach to describe an arbitrarily dense polymer interface (layer made of overlapping polymer chains). Our analysis is based on a description of the layer in terms of loops and tails. Within a simple scaling model for the behavior of the loops and tails, we are able to relate the features of…
Chemically stable poly[2-(3,5-di- tert -butyl-4-oxyphenyl)-1,4( p )-phenylenevinylene], poly[4-(3,5-di- tert -butyl-4-oxyphenyl)-1,3( m )-phenylenevinylene], and poly[4-(3,5-di- tert -butyl-4-oxyphenyl)-1,2( o )-phenylenevinylene] were synthesized via the polymerization of 4-bromo-2-(3,5-di- tert -butyl-4-acetoxypheny…
Transition-metal carbide nanorods have been prepared by reacting carbon nanotubes with volatile Ti and Nb iodides. Systematic temperature-dependent growth studies of TiC nanorods produced from spatially separated Ti metal and carbon nanotubes in the presence of iodine have shown that reaction proceeds initially via th…
Spectral data for HCOOH oxidation at Pt(111), Pt(100), and Pt(110) are presented and discussed. Spectra were taken shortly after the surfaces were contacted with a 0.1 M HCOOH/0.1 M HClO 4 solution at a controlled potential of 0.05 V vs RHE and give information on the adsorption and oxidation processes at the early st…
Disjoining pressure isotherms for foam films made from a nonionic surfactant, octyl β-glucoside, are measured at different surfactant concentrations, ionic strengths, and solution pH values. Below the cmc an electrostatic double-layer repulsion is present and dominates the long-range interaction. The decay length of t…
Tetrahedral Al-containing MCM-41, prepared under ambient conditions, exhibits suitable catalytic properties for the conversion of low-density polyethylene into hydrocarbon feedstocks.
It has been found that mesoporous structures of MCM-41 and MCM-48 disintegrate readily in distilled water around 370 K, while the structures can be stable in 100%-steam of 1 atmospheric pressure at much higher temperatures around 820 K. Thus, the structure disintegration is thermodynamically more favorable in water th…
Recent studies of molecular orientation in sheared liquid crystalline polymers have often yielded contradictory results. To check the self-consistency of methods for quantitative measurements of molecular orientation, liquid crystalline solutions of (hydroxypropyl)cellulose [HPC] and poly(benzyl glutamate) [PBG] have…
New hybrid organic–inorganic materials are prepared by hydrolysis and polycondensation, or cocondensation with tetraethyoxysilane, of iron porphyrins bearing a trifluorosily function; despite their insolubility, these ‘metalloporphyrinosilicas’ are efficient catalysts for alkene epoxidation by PhiO or ButOOh and alkan…
U. Schubert, J. Chem. Soc., Dalton Trans., 1996, 3343 DOI: 10.1039/DT9960003343
A small cluster model is proposed and used to examine the properties of bound Cu ions and their interactions with CO and NO in Cu-exchanged zeolites, such as Cu−ZSM-5. The model uses H 2 O ligands to represent the framework oxygens of the zeolite lattice that form the local coordination environment of the Cu ion. Vari…
The redox behavior of CuZSM-5 was investigated by flow microbalance and FTIR measurements using CO and NO as probe molecules. The weight change resulting from switching the flow of 10% O 2 in He to pure He corresponded to the removal of extralattice oxygen and approximately 20% autoreduction of total copper ion by one…
A water soluble β-cyclodextrin (CD-NA) bearing seven naphthoyl chromophores forms very stable 1:1 complexes with a merocyanine laser dye DCM-OH (4-(dicyanomethylene)-2-methyl-6-( p -(bis(hydroxyethyl)amino)styryl)-4 H -pyran). The antenna effect, i.e. energy transfer from the naphthoyl antenna chromomophores to the en…
The hydrothermal reaction of manganese dichloride with the potassium salt of benzene-1,3,5-tricarboxylic acid at 220 °C gives [Mn3{C6H3(CO2)3-1,3,5}2] which exhibits two pathways for antiferromagnetic coupling.
Having previously demonstrated the possibility of synthesizing high molecular weight poly(ether imide)s with ortho -linked main-chain units from bis(ether anhydride)s derived from catechol or its derivatives, we now provide a preliminary assessment of the properties of the polymers prepared from the catechol bis(ether…
The structure of (porphinato)nickel(II) [Ni(P)] has been determined by X-ray diffraction and inferred from a combination of single-crystal and solution resonance Raman measurements. The crystal structure reveals a planar porphyrin macrocycle with a π−π dimer packing configuration exhibiting a small lateral shift. This…