Materials Literature
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Competition between polaron and bipolaron inconjugated polymers with nondegenerate ground state is systematically studied in the extended Hubbard-Peierls model with the symmetry-breaking Brazovskii-Kirova term, using the density matrix renormalization group method combined with lattice optimization in the adiabatic ap…
Ab initio multi-reference configuration interaction calculations are performed for the Si(100) surface using a cluster approach. The convergence with respect to the cluster size is checked and the final results are taken from a $Si_{32} H_{28}$ cluster which models two dimers and six bulk layers. We find for the ideal…
With the aim to get an insight in the origin of differences in the earlier reported calculation results for KNbO3 and to test the recently proposed implementation of the FP-LMTO method by Methfessel and van Schilfgaarde, we perform a comparative study of the ferroelectric instability in KNbO3 by FP-LMTO and LAPW metho…
A revised Marko-Siggia elastic model for DNA double helix [Macromolecules 27, 981 (1994)] is proposed, which includes the WLC bending energy and a new chiral twisting energy term. It is predicted that the mean helical repeat length (HRL) for short DNA rings increases with the decreasing of chain length; while for very…
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” opt…
Tetrameric ruthenium(II) porphyrin complexes, [Ru(4-PyP 3 P)(CO)] 4, 1, [Ru(4-PyT 3 P)(CO)] 4, 2, and [Ru(4-PyT 3 P)(Py)] 4, 3, (4-PyP 3 P = 5-(4-pyridyl)-10,15,20-triphenylporphyrinato dianion, 4-PyT 3 P = 5-(4-pyridyl)-10,15,20-tritolylporphyrinato dianion), were self-assembled and were characterized by 1 H NMR, IR,…
The electronic and electrochemical properties of a carbon monoxide−FeTMPP adduct (FeTMPP = (5,10,15,20-tetrakis[4-methoxyphenyl]-21 H,23 H -porphine)iron(II)) adsorbed on Black Pearls (BP) high-area carbon have been examined in situ in 0.05 M H 2 SO 4 by Fe K-edge X-ray absorption near-edge structure (XANES). This add…
The use of nitrones as ligands was explored by preparing and characterizing complexes of N - tert -butyl-α-(2-pyridyl)nitrone (2-PyBN) and 2,5,5-trimethyl-1-pyrroline- N -oxide (M 3 PO) with Cu(II), Mn(II), Co(II), Ni(II), Fe(II), and Fe(III) hexafluoroacetylacetonates (hfac). Neutral Cu(2-PyBN)(hfac) 2, 1, was formed…
An attempt is made to draw conclusions on the binding situation and the electronic state of nickel in the hexagonal perovskite BaNiO 3 characterized by chain units of face sharing NiO 6 octahedra by means of XPS, IR, and Mössbauer spectroscopy and susceptibility measurements. Although the results of Mössbauer measurem…
The angular dependence of the magnetic properties of all known octahedrally coordinated oxo-bridged dimers with trivalent 3d transition metals are interpreted in terms of the most simple concepts. These concepts are based on a combination of kinetic exchange and the chemically intuitive angular overlap model. The use…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSynthesis, Spectroscopy, and Morphology of TetrastilbenoidmethanesWarren J. Oldham, Jr.†, Rene J. Lachicotte, and Guillermo C. Bazan*View Author Information Department of Chemistry, University of Rochester Rochester, New York 14627 † Current address: FED Corporation, H…
The osmium tetroxide-mediated dihydroxylation of meso -tetraphenylporphyrin leads to the formation of the vic -diol meso -tetraphenyl-2,3- vic -diol-2,3-chlorin. The corresponding Ni(II) complex was converted by lead tetraacetate into ( meso -tetraphenyl-2,3-secochlorinato-2,3-dialdehyde)nickel(II). This novel pigment…
Geometries and force-fields of the low-lying spin states of iron(II) porphine are calulated with nonlocal density functional methods. The ground state is identified as the 3 A 2g state. It is shown that the Fe atom is in the porphine plane for all spin states, but that the high-spin state potential surface intersects…
The Pyrococcus furiosus (PF) ornithine carbamoyltransferase (OTCase; EC 2.1.3.3) is an extremely heat-stable enzyme that maintains about 50% of its activity after heat treatment for 60 min at 100 degrees C. To understand the molecular basis of thermostability of this enzyme, we have determined its three-dimensional st…
Quantum disc structures (with diameters of 200 nm and 100 nm) were prepared from a Zn_{0.72}Mn_{0.28}Se/ZnSe single quantum well structure by electron beam lithography followed by an etching procedure which combined dry and wet etching techniques. The quantum disc structures and the parent structure were studied by ph…
Sonoluminescence, a resonant cavitation of the gas/liquid interface with the kHz ultrasound, produces visible light and splitting of water. According to the quantum vacuum radiation model of sonoluminescence, high- $Q$ resonant radio frequency (rf) or microwave cavity with movable walls should produce similar effects.…
Although the intensity parameters and especially the parameter can show a considerable spread for a particular lanthanide ion in different host matrices, the values of these parameters for lanthanide ions in glasses are relatively close to each other. Combined with the fact that large errors are inherent to these para…
Lewis acid and Lewis base centers are simultaneously present in the boron-bridged thiophene-containing porphyrinogen 1 that has been synthesized in high yield. Its crystal structure reveals a nonplanar macrocycle; this and the colorless aspect suggest the absence of a delocalized π-electron system. R = NiPr2.
The liquid crystalline behavior of compounds 1 (n = 7, 12, 15) differs significantly from that exhibited for conventional rodlike molecules. They organize into layered smectic, bicontinuous cubic or hexagonal columnar mesophases depending on the temperature or the volume fraction of coil segments.
A first-principle molecular dynamics study on liquid $\mathrm{GeSe}{}_{2}$ yields structural properties in good agreement with detailed neutron scattering data. The short range order is accurately described by a variety of bonding configurations, in which regular tetrahedra coexist with an important fraction of homopo…