Materials Literature
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Four unsymmetrical covalently linked porphyrin dimers were synthesized, and their electrochemical, spectroelectrochemical, and/or photophysical properties were examined. The investigated compounds are represented as M[ p -(TPP-DEHMP)]M and M[ m -(TPP-DEHMP)]M (M = H 2, Zn), where p -(TPP-DEHMP) is the tetraanion of 1-…
This paper discusses the dynamic interfacial tension (IFT) variation in a system containing an acidic oil in contact with an alkaline solution which may contain a preformed surfactant. A modified technique similar, in principle, to the sessile drop technique is used for monitoring the dynamic IFT which is in the ultra…
The structure of QUI-MnGS-1 has been determined from single-crystal X-ray diffraction on a ∼0.03 × 0.03 × 0.02 mm sample using synchrotron radiation. This material [(C 7 H 13 N)Mn 0.25 Ge 1.75 S 4 ·H 2 O] crystallizes in space group I 4̄2 d with unit cell a = 11.581(1) and c = 18.741(3) Å. The extended framework of th…
The compound Cs 3 Te 22 is well-known for its interesting structural features. It contains both a unique 2,3-connected defect square Te sheet and Te 8 rings. For a better understanding of the structure and bonding, the band structure of Cs 3 Te 22 is examined by means of the ab initio tight-binding linear muffin-tin o…
The phase diagram of a protein−water system is described with a simple model with parameters for the interaction between protein molecules in the liquid and in the solid phase. The model reproduces essential features of the phase diagram, such as the (metastable) liquid−liquid immiscibility region and the triple point…
A pair of tropinone reductases (TRs) share 64% of the same amino acid residues and belong to the short-chain dehydrogenase/reductase family. In the synthesis of tropane alkaloids in several medicinal plants, the TRs reduce a carbonyl group of an alkaloid intermediate, tropinone, to hydroxy groups with different diaste…
As part of a structure-aided effort to design clinically useful inhibitors of metallo-beta-lactamases, the X-ray crystal structure of a complex between the metallo-beta-lactamase from Bacteroides fragilis and 4-morpholinoethanesulfonic acid (MES) has been determined and a model for the structure has been refined to a…
A series of benzyl-substituted phthalonitriles, substituted at the 3-, 4-, and 4,5-positions, underwent varied condensations with phthalonitrile to give a series of protected (monohydroxy- and polyhydroxyphthalocyaninato)zinc(II) derivatives which were readily cleaved to give several hydroxyphthalocyanines (ZnPc) (pht…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTDerivatization of Porous Silicon by Grignard Reagents at Room TemperatureNamyong Y. Kim and Paul E. LaibinisView Author Information Departments of Chemistry and Chemical Engineering Massachusetts Institute of Technology Cambridge, Massachusetts 02139 Cite this: J. Am.…
The crystal structure of syndiotactic polystyrene (sPS) in its stable α form (a so-called “superstructure” named α‘‘) is reevaluated. As shown by all previous investigations, the trigonal unit cell contains three triplets of extended sPS chains. The azimuthal orientation of the three triplets is shown to differ from t…
A series of neutral pyridyl adducts involving the strong Lewis acids BF 3 and B(C 6 F 5 ) 3 has been prepared, and their second-order nonlinear optical coefficients (EFISH method) have been examined. The formation of the pyridyl−boron bond leads to enhancement of the dipole moments and second-order NLO coefficients (β…
The photochemistry of a molecular triad consisting of a porphyrin (P) covalently linked to a carotenoid polyene (C) and a fullerene derivative (C 60 ) has been studied at 20 K by time-resolved EPR spectroscopy following laser excitation. Excitation of the porphyrin moiety yields C− 1 P−C 60, which decays by photoinduc…
The established macroscopic equations of motion for two phase immiscible displacement in porous media are known to be physically incomplete because they do not contain the surface tension and surface areas governing capillary phenomena. Therefore a more general system of macroscopic equations is derived here which inc…
The glass transition temperature ( T g ) of layers of stereoregular poly(methyl methacrylate) (PMMA) spin-cast on silicon and aluminum surfaces has been investigated by ellipsometry. The interfacial specific interactions were highlighted and quantified by infrared reflection absorption spectroscopy. It was found that…
Zirconia-supported tungsten oxide catalysts were prepared by suspending hydrous zirconium oxide in aqueous solutions of ammonium metatungstate at their natural pH. The suspensions were refluxed at 383 K followed by evaporation of the water, drying and calcination. The WO 3 loadings were chosen between 3.6 and 32 wt %…
Several strategies are reported that allow carbon black (CB) particles to be selectively localized at the interface of polyethylene/polystyrene (PE/PS) blends used as models of two-phase polyblends. A first general approach relies upon a kinetic control, i.e., the choice of such processing conditions that the CB parti…
The bias-enhanced nucleation of diamond on Si(100) has been studied by x-ray absorption near-edge spectroscopy (XANES) and atomic force microscopy, two techniques well suited to characterize nanometric crystallites. Diamond nuclei of ∼15 nm are formed after 5 min of bias-enhanced treatment. The number of nuclei and it…
Field emission properties of undoped chemical vapor deposited diamond and diamondlike carbon films have been measured for a variety of different deposition conditions. The nature and appearance of the damage site after testing, together with the mathematical form of the observed current–voltage relations, are correlat…
Thin films of Ag2Te were obtained by vapor transport and electron beam evaporation methods. The film phase and chemical compositions were analyzed by x-ray diffraction and x-ray photoelectron spectroscopy analyses, respectively. Film composition was close to stoichiometric with a slight excess of tellurium. Strong (1̄…
We study the equilibrium phase diagram of binary mixtures of hard spheres as well as of parallel hard cubes. A superior cluster algorithm allows us to establish and to access the demixed phase for both systems and to investigate the subtle interplay between short-range depletion and long-range demixing.