201 research outputs found
Corallistine, a new polynitrogen compound from the sponge Corallistes fulvodesmus L. and L.
Two polynitrogen compounds 1-methyl-pteridine-2,4-dione 1b and corallistine 2 were isolated from the new-caledonian sponge #Corallistes fulvodesmus$ L. & L. The structure of corallistine was determinated by X-ray single crystal analysis of its 6'-isobutyloxycarbonyl derivative 3. (Résumé d'auteur
Structure (X-Ray) analysis of manicoline B, a mixture of two diastereoisomers of a new alkaloid from Dulacia guianensis (Olacaceae)
Isolation and structure (X-Ray analysis) of manicolina A, a new-aminotropone from Dulacia guianensis (Olacaceae)
Isolation and structure (X-ray analysis) of karinolide, a new quassinoid from Simaba multiflora
An indole alkaloid from Strychnos erichsonii
Le premier alcaloïde indolique de type vobasine rencontré dans les #Loganiaceae a été isolé des écorces de #Strychnos erichsonii, récoltées en Guyane Française. Sa structure confirmée par cristallographie Rx. (Résumé d'auteur
Manicol : a sesquiterpenoid hydroxytropolone from Dulacia guianensis; a revised structure (X-ray analysis)
Computational Lattice-Gas Modeling of the Electrosorption of Small Molecules and Ions
We present two recent applications of lattice-gas modeling techniques to
electrochemical adsorption on catalytically active metal substrates: urea on
Pt(100) and (bi)sulfate on Rh(111). Both involve the specific adsorption of
small molecules or ions on well-characterized single-crystal electrodes, and
they provide a particularly good fit between the adsorbate geometry and the
substrate structure. The close geometric fit facilitates the formation of
ordered submonolayer adsorbate phases in a range of electrode potential
positive of the range in which an adsorbed monolayer of hydrogen is stable. In
both systems the ordered-phase region is separated from the adsorbed- hydrogen
region by a phase transition, signified in cyclic voltammograms by a sharp
current peak. Based on data from {\it in situ\/} radiochemical surface
concentration measurements, cyclic voltammetry, and scanning tunneling micro-
scopy, and {\it ex situ\/} Auger electron spectroscopy and low-energy electron
diffraction, we have developed specific lattice-gas models for the two systems.
These models were studied by group-theoretical ground-state calcu- lations and
numerical Monte Carlo simulations, and effective lattice-gas inter- action
parameters were determined so as to provide agreement with experiments.Comment: 17 pp. uuencoded postscript, FSU-SCRI-94C-9
- …