Materials Literature
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Small-angle neutron scattering (SANS) has been used to investigate the thermal concentration fluctuations in a single-phase state of binary polymer mixtures such as deuterated polystyrene (DPS)/poly(vinyl methyl ether) (PVME), deuterated polybutadiene (DPB)/protonated polybutadiene (HPB), and DPB/protonated polyisopre…
X-ray scattering has been used to investigate the structures of Kr, Xe, and N 2 monolayers adsorbed on the basal plane of boron nitride. The results indicate that all three monolayers form a 2D solid of the simple triangular structure. Both Kr and N 2 monolayers are commensurate with respect to the substrate only in v…
The molecular and electronic structures of TCNQ and its π-extended derivatives benzo-TCNQ and TCAQ have been investigated using the semiempirical PM3 method and ab initio 6-31G* calculations. The steric hindrance introduced by lateral benzoannulation determines the loss of planarity of the TCNQ moiety for benzo-TCNQ a…
A new pyrazolate-bridged tetranuclear copper(II) complex [{CuL(H2O)}4]·12H2O (H2L = 5-methoxycarbonylpyrazole-3-carboxylic acid) was synthesized and its crystal structure determined. The molecule has C2 symmetry and consists of four copper atoms bridged by four planar L ligands through the nitrogen atoms of the pyrazo…
Investigations were done on the enhanced aqueous solubility of glibenclamide. Eight kin & of glibenclamide coprecipitates, using two kinds of polyvinylpyrrolidone (PVP) having different molecular weights, were prepared in a solid powdered form by the conventional evaporation method. The formation of coprecipitates was…
Density functional calculations within the Car−Parrinello framework are used to obtain self-consistently the electronic and the geometrical structures of polythiophene derivatives. The relation between the electronic states and quinoid vs aromatic structures is studied on a series of substituted polythiophenes (PTh) a…
New examples of terminal group 5 chalcogenido-substituted polytungstates with the Keggin [PW11O39ME]4- (M = Nb, Ta; E = S, Se) (pictured) and Lindquist [W5O18NbSe]3- structures have been prepared by oxo/chalcogenido ligand substitution reactions. The compounds and their reactions with H2O in nonaqueous solution were c…
We present a nonlinear dynamical model for oscillatory zoning in plagioclase based on a simple isothermal constitutive undercooling mechanism. A phenomenological partitioning is introduced to relate the concentration of An in the melt at the interface with the concentration in the solid. The non‐linearities in the mod…
Synthetic procedures are described that allow access to the [V(3)O(O(2)CR)(6)L(3)](ClO(4)) (R = various groups; L = pyridine (py), 4-picoline (pic) or 3,5-lutidine (lut)) family of complexes. Treatment of VCl(3)(THF)(3) with NaO(2)CR (R = Me, Et) in RCO(2)H/py, pic/MeCN, or CH(2)Cl(2) solution followed by addition of…
The nitrosoarene ligands in ferrous [FeII(tpp)(PhNO)2] are bound through their nitrogen atoms, whereas they are bound through their oxygen atoms in ferric [FeIII(tpp)(Et2NC6H4NO)2]SbF6.
Small-angle neutron scattering (SANS) was used to probe the thermodynamic interactions in multicomponent polymer blends including ternary blends containing two homopolymers and a block copolymer, mixtures of a homopolymer and a block copolymer, and a blend of two block copolymers. The polymers used for this study were…
The syntheses, properties, and characterization of several new complexes, Re(CN t Bu) 3 (PCy 3 ) 2 H ( 1a ), Re(CN t Bu) 3 (PR 3 ) 2 Cl [R = Cy, Ph ( 2a, 2b )], the 17-electron [Re(CN t Bu) 3 (PCy 3 ) 2 Cl] + ( 3a ), the dihydrogen complex, [Re(CN t Bu) 3 (PR 3 ) 2 (H 2 )] + [R = Cy, Ph ( 4a, 4b )], the coordinatively…
The electronic structure and bonding of the N 2 S 2 molecule are studied by the spin-coupled valence bond method. Unusual features are revealed which clarify much of the hitherto puzzling properties of this molecule, leading ultimately to a simple Lewis structure: The two N atoms of the N 2 S 2 ring bear a substantial…
Crystals of (15-crown-5)2KTCNQ adopt a solid-state architecture built up from isolated TCNQ•- dimer units surrounded by crown-encapsulated cation “barrels” with no evidence for direct counterion interaction. The structural and spectroscopic behavior of this material therefore provides a valuable model for the solid-st…
X-ray fiber diagrams of the aromatic copolyamide Technora, prepared from terephthaloyl chloride and equimolar proportions of p -phenylenediamine and 3,4‘-diaminodiphenyl ether, contain a series of nonperiodic layer lines that point to a structure consisting of parallel chains of random comonomer sequence. The meridion…
(γ-Aminopropyl)triethoxysilane (APTES) and simpler molecules having at least one common function with APTES (i.e., propylamine and mono-, di-, or triethoxyalkylsilane) were adsorbed at the silica/heptane interface at 25 °C. The hydrolysis of ethoxy functions by surface water is observed only for APTES, which stresses…
Adiabatic heat capacity measurements were made on triphenylphosphite, molecular formula C 18 H 15 O 3 P, between 140 and 335 K. The results confirm the existence of a phase which is intermediate in stability between the undercooled liquid and the crystal phase. This phase, called the glacial phase, was recently report…
Article Definitions of terms relating to degradation, aging, and related chemical transformations of polymers (IUPAC Recommendations 1996) was published on January 1, 1996 in the journal Pure and Applied Chemistry (volume 68, issue 12).
Photoreduction of [SbV(tpp)(OH)2]+(tpp = dianion of 5,10,15,20-tetraphenylporphyrin) yields either the metastable π-radical anion [SbV(tpp˙–)(OH)2] or the two-electron reduced[SbIII(tpp)]+ complex; product formation can be channelled in the desired direction by an appropriate choice of the reaction medium and dioxygen…
According to the Rietveld refinement, Ca2CrNbO6 and Sr2CrNbO6 have been found to be monoclinic with a= 5.4195 (1)Å, b= 5.4907 (1)Å, c= 7.7073 (2)Å, and cubic with a= 7.8732 (1)Å(Fmtext-decoration:overline3m, No. 225), respectively. Under atmospheric pressure, Ba2CrNbO6 crystallizes into an 8H hexagonal structure with…