The Comparison of the Orientation of Sodium 3-Hydroxy-2-Naphthalenecarboxylate in the Cavity of β-Cyclodextrin and Heptakis-(2,3,6-Tri-O-Methyl)-β-Cyclodextrin

Conformational analysis of inclusion complexes of sodium 3-hydroxy-2-naphthalenecarboxylate with v2/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin and heptakis-(2,3,6-tri-o-methyl)-v2/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin in D₂O was investigated by 1D and 2D ¹HNMR measurements. The results show that part of the naphthyl group of sodium 3-hydroxy-2-naphthalenecarboxylate is situated in the 2,3-OH side of the v2/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin cavity asymmetrically while the whole naphthyl group is included in the heptakis-(2,3,6-tri-o-methyl)-v2/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin cavity with the caboxylate and hydroxy group close to the 6-OCH₃ group.     

Triterpene glycosides ofFatsia japonica. I. Isolation and structure of glycosides fromFatsia japonica seeds

The known triterpene glycosides hederagenin 3-O-v4512/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-L-arabinopyranoside, hederagenin 3-O-\-D-glucopyranoside, oleanolic acid 3-O-v4512/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-sophoroside, hederagenin 3-O-v4512/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-sophoroside, and their 28-O-v4512/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-gentiobiosyl esters, respectively, in addition to the new triterpene glycoside 3-O-v4512/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-sophorosyl-28-O-v4512/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-L-rhamnopyranosyl-(1v4512/xxlarge8594.gif" alt="rarr" align="BASELINE" BORDER="0">4)-O-v4512/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-gentiobiosyl hederagenin are isolated fromFatsia japonica (Araliaceae) seeds. The structures of these glycosides are established using chemical and spectral methods.Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 131–133, March–April, 2000.     

About a minimax theorem of Matthies,Strang and Christiansen

We give a new minisup theorem for noncompact strategy sets. Our result is of the type of the Matthies-Strang-Christiansen minimax theorem where the hyperplane should be replaced by any closed convex set. As an application, we derive a slight generalization of the Matthies-Strang-Christiansen minimax theorem.     

2,6-Di-tert-butylphenols and phenoxyl radicals with metal—metal bonds

v12/xxlarge963.gif" alt="sgr" align="BASELINE" BORDER="0">-Aryl trans-bistriphenylphosphine complexes based on 2,6-di-tert-butylphenol containing Pt—SnCl₃, Pt—GeCl₃ groups were synthesized. Oxidation of these compounds gives the corresponding phenoxyl radicals, which were studied by ESR spectroscopy. The transformation of the diamagnetic complexes to the paramagnetic state is accompanied by cleavage of the Pt—Sn, Pt—Ge bonds and by elimination of SnCl₂, GeCl₂.     

Synthesis of (α-substituted α-aminophosphinic and α-aminophosphonic acids

The reaction of ketoximes with hypophosphorous acid resulted in previously unknown v664h32180353437/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-substituted-v664h32180353437/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-aminophosphinic acids, which were oxidized into the corresponding v664h32180353437/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-substituted-v664h32180353437/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-aminophosphonic acids.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2729–2732, November, 1996.     

1,3-Dipolar cycloaddition of cyclic α-methoxynitrones, derivatives of 2H-imidazole 1-oxide and 4H-imidazole 3-oxide

The reactions of cyclic aldo- and v8u6800716p430/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-methoxynitrones of the 2H-imidazole-1-oxide and 4H-imidazole 3-oxide series with isocyanates, phenyl isothiocyanate, N-phenylmaleimide, and dimethyl acetylenedicarboxylate were studied. The reactions give the corresponding 1,3-dipolar cycloaddition products. 2,2-Dimethyl-4-phenyl-2H-imidazole 1-oxide does not enter into a similar reaction with isocyanates or phenyl isothiocyanate.     

AlSiP3, a compound with a novel wurtzite-pyrite intergrowth structure

AlSiP₃ is formed by heating aluminum and silicon powder with red phosphorus and adding small amounts of iodine or AlCl₃. Small, black crystals with metallic lustre grow at 1200°K. The compound crystallizes in the orthorhombic space group Pmnb (No. 62) with a = 987.2 pm, b = 586.1 pm, c = 608.8 pm and four formula units. In the structure isolated P atoms as well as P₂ pairs are present (PP = 218.2 pm). Silicon is tetrahedrally bonded (SiP = 224.2 ? 228.2 pm) whereas aluminum has octahedral coordination (AlP = 244.2 – 260.8 pm). The structure can be described as an intergrowth structure of wurtzite and pyrite type.     

Relative stability of the2 A 1g and2 E g states of the C2H 6 + ion

Anab initio study of the relative stability for the states² A _1g and² E _g of C₂H ₆ ⁺ has been carried out. The results of the Open Shell Restricted Hartree-Fock calculations lead to assign the² A _{1 g} as the ground state of the molecule in agreement with previous SCF calculations.The correlation energy associated to both states has been calculated within the correlation hole model and the results, contrary to those obtained from Configuration Interaction calculations, do not alter qualitatively the conclusions from SCF.     

The contrast gain in a guest-host nematic display due to a periodic boundary condition

The mean square tilt angle of a nematic slab with finite anchoring energy and periodic boundary conditions has been theoretically investigated, as a function of the slab geometry and of the reduced extrapolation length. If the anchoring strength is free-surfacelike, the contrast is affected by a loss 10% at room temperature if the ratio between the anchoring pitch and the cell thickness is 0.5.Glossary anchoring pitch - h cell thickness - /h - ( = x/, = y/h) reduced coordinates - v" align="BASELINE" BORDER="0">(, ) local tilt angle - elastic constant - w_a anchoring energy anisotropy - b=/w _a de Gennes-Kleman extrapolation length - B=b/h reduced extrapolation length - T _NI nematic-isotropic transition temperature - :=(T/T _NI ) – 1 reduced temperature - easy axis direction - _MAX - v" align="BASELINE" BORDER="0"> _± ² mean square tilt angle along the boundary - () absorbance coefficients of the p-dye - r /: dichroic ratio - c contrast - G contrast gain - S order parameter     

Charge-transfer complexes of indenophanes with π-acceptors

The charge-transfer (CT) spectra of the v270704n18/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-complexes formed by a number of v270704n18/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-acceptors with several indenophanes as well as indene as a model compound have been measured in methylene chloride at 20 °C. Association constants and transition energies of these complexes as well as ionization potentials of the v270704n18/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-donors have been determined. The data obtained indicate the existence of transannular electronic interactions in the indenophane nucleus. Furthermore, the pseudo-para- andmeta[2.2]indenophane isomers (3 and4) show a large difference in their v270704n18/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-base strength. A good linear relationship has been observed between the association constants and v270704n18/xxlarge955.gif" alt="lambda" align="BASELINE" BORDER="0">_max of the long wavelength CT bands for the v270704n18/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-complexes of these v270704n18/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-donors with both tetracyanoethylene (TCNE) and 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ). All CT complexes studied have a 1:1 stoichiometry.

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Charge-transfer-Komplexe aus Indenophanen und v270704n18/xhuge960.gif" alt="pgr" align="BASELINE" BORDER="0">-Akzeptoren

Zusammenfassung Die Charge-transfer-Spektren (CT-Spektren) von v270704n18/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-Komplexen aus Indenophanen bzw. der Modellverbindung Inden und verschiedenen v270704n18/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-Akzeptoren wurden in Methylenchlorid bei 20 °C bestimmt. Die Assoziationskonstanten und Übergangsenergien dieser Komplexe sowie die Ionisationspotentiale der v270704n18/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-Donatoren wurden ermittelt. Die Daten sprechen für das Vorliegen transannularer elektronischer Wechselwirkungen im Indenophan-System. Die isomeren pseudo-para- und -meta[2.2]indenophane3 und4 unterscheiden sich in ihrer v270704n18/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-Basizität deutlich. Es besteht eine gute lineare Korrelation zwischen den Assoziationskonstanten und v270704n18/xxlarge955.gif" alt="lambda" align="BASELINE" BORDER="0">_max der langwelligen CT-Banden der verschiedenen v270704n18/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-Donatoren mit Tetracyanoethylen (TCNE) und 2,3-Dichlor-5,6-dicyano-p-benzochinon (DDQ). Alle untersuchten CT-Komplexe besitzen 1:1-Stöchiometrie.