Materials Literature
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Abstract: Carbohydrate researchers may think it is reasonable to believe that the synthesis and structure of a crystalline b-1,4 glucan would be quite straightforward; however, this is not the case. The pitfalls and detours of research have been counterbalanced by exciting new discoveries in cellulose structure, biosy…
DFT calculations have been carried out on the titanium carbide clusters Ti 3 C 8, Ti 4 C 8, Ti 6 C 13, and Ti 7 C 13 and their anions, in relation with the recent experimental and theoretical report by L.-S. Wang and his group on those clusters (Wang, L.-S.; Wang, X.-B.; Wu, H.; Cheng, H. J. Am. Chem. Soc . 1998, 120,…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTElectrochemical Reduction of Pyrrole in the Presence of Trinitrofluorenone: Isolation of a Meisenheimer ComplexKatsuyoshi Hoshino, Nobuo Ozawa, Hiroshi Kokado, Hiroko Seki, Tatsuhiro Tokunaga, and Tsutomu IshikawaView Author Information Faculty of Engineering, Chemical…
PE−EP and PE−EP−EPDM block polymers have been made in yields exceeding 70% with Ziegler−Natta catalysts by matching the polymerization time for each block to chain growth time and catalyst decay rates. A short residence time tubular flow reactor with multiple side stream feeds was used to accomplish this result. The a…
Density functional calculations were performed on 1,1‘,5,5‘-tetramethyl-6,6‘-dioxo-3,3‘-biverdazyl diradical (BVD) and BVD[CuI(PL 3 )] 2 complexes (L = H, Me, OH, OMe, F) in order to investigate how Cu chelation affects the singlet−triplet splitting of the verdazyl system. It was found that donating ligands on Cu dest…
Square-planar rhodium or iridium “ n -decyloxy-β-diketonate” complexes of the general formula [M(β-diketonate)(CO) 2 ] (M = Rh ( 1 − 3 ) or Ir ( 4 − 6 )) and pyrazole−rhodium derivatives of the type [RhCl(CO) 2 (pyrazole)] ( 7 − 9 ) have been prepared and their liquid-crystalline properties studied. Compounds 1 and 4…
While ongoing efforts continue to explore the high-pressure phase equilibria of polymer blends, few studies have attempted to address the impact of a supercritical (sc) fluid on such equilibria. In this work, we report on the phase behavior of an upper critical solution temperature (UCST) polymer blend in the presence…
The 1 H NMR spectra of iron(III) complexes of dimeric 5,5‘-bis(10,15,20-triphenylporphyrin) [(TrPPH 2 ) 2 ], 5,5‘-bis(10,15,20-tris( p -methoxyphenyl)porphyrin) [(Tr( p -MeOP)PH 2 ) 2 ], and hybrid (TrPPH 2 )(Tr( p -MeOP)PH 2 ) and the respective monomeric 5,10,15-triphenylporphyrin (TrPPH 2 ) and 5,10,15-tris( p -met…
Continuous crystallization of calcium lactate pentahydrate was investigated in a mixed-suspension-mixed-product removal crystallizer. Wide ranges of the mean residence time, relative supersaturation, and magma density were covered (40−215 min, 0.01−1.12, and 2−65 kg/m 3, respectively). Crystal growth was found to be d…
Unique temperature-dependent syn-anti conformational switching in bis- and monozinc ethane-bridged porphyrin dimers takes place in nonpolar solvents containing a small amount of alcohol (1−5%). These dimers adopt a syn conformation at any studied temperatures in the absence of alcohol added, while, in the presence of…
The formation of a molecular assembly composed of a naturally occurring peptide with a helical structure was investigated. Gramicidin A, a 15-mer peptide antibiotic, was conjugated with poly(ethylene glycol) (PEG, average molecular weight 600). This peptide conjugate formed vesicles with an unilamellar membrane in wat…
The nature of the structural ordering within semicrystalline poly(3-dodecylthiophene) films has been analyzed using a Warren−Averbach line-shape analysis which includes up to five orders of the ( h 00) lattice reflections. This analysis yields a semiquantitative measure of the volume averaged crystallite sizes, the la…
Nonlinear optical (NLO) properties of two series of octupolar molecules are investigated to establish the structure−NLO-property relationships by carrying out the ab initio (HF/6-31G) calculations of the molecular polarizability (α), the first hyperpolarizability (β), and the second hyperpolarizability (γ). It is foun…
Non-heme Fe(II) proteins form stable nitrosyl adducts. However, there are few synthetic examples of structurally characterized non-heme iron nitrosyl complexes, especially those that are coordinatively unsaturated. Presented herein is a series of non-heme {Fe−NO} 7 complexes with trigonal bipyramidal coordination geom…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTAntiferromagnetic Organic Metal Exhibiting Superconducting Transition, κ-(BETS)2FeBr4 [BETS = Bis(ethylenedithio)tetraselenafulvalene]Emiko Ojima, Hideki Fujiwara, Kiyonori Kato, Hayao Kobayashi, Hisashi Tanaka, Akiko Kobayashi, Madoka Tokumoto, and Patrick CassouxView…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTA New Approach for the Design of Supramolecular Recognition Units: Hydrogen-Bonded Molecular DuplexesBing Gong, Yinfa Yan, Huaqiang Zeng, Ewa Skrzypczak-Jankunn, Yong Wah Kim, Jin Zhu, and Harold IckesView Author Information Department of Chemistry The University of To…
We study a two-dimensional honeycomb lattice gas model with both nearest- and next-nearest-neighbor interactions in a staggered field, which describes the surface of stoichiometrically binary crystal. We calculate anisotropic step tension, step stiffness, and equilibrium island shape, by an extended random walk method…
A Monte-carlo (MC) simulation procedure has been developed where the pair bond energies are allowed to take into account the various coordination numbers of surface atoms and the presence of adsorbates. The pair bond energies are calculated from partial bond energies of atoms which, in turn, are calculated from modifi…
We present a multigrid algorithm for self consistent solution of the Kohn-Sham equations in real space. The entire problem is discretized on a real space mesh with a high order finite difference representation. The resulting self consistent equations are solved on a heirarchy of grids of increasing resolution with a n…
We apply first principles calculations to study the opening of single-wall carbon nanotubes (SWNT's) by oxidation. We show that an oxygen rim can stabilize the edge of the open tube. The sublimation of CO$_2$ molecules from the rim with the subsequent closing of the tube changes from endothermic to exothermic as the t…