Resonance fluorescence spectrum of nitrogen dioxide

We report an investigation of the resonance fluorescence spectrum of NO₂ excited by several laser lines. Sixty transitions, mostly in ν₂ progressions of the ground state, have been assigned. Analysis of the spectra extend the knowledge of the ground state constants, especially of the anharmonic coefficients. It is possible to establish that transitions are occurring to a ²B₁ state and to a ²B₂ state in the same energy region.     

Role of hydroxyl groups in the stereochemistry of hydrogen transfer from chiral NAD(P)H model to carbonyl

Asymmetric reduction of α-ketoester with a chiral dihydronicotinamide was significantly affected by chiral aromatic additives, capable of exerting an attractive interaction with dihydropyridine ring, which was further consolidated through with magnesium.     

Concise synthesis of dl-febrifugine

Racemic compound (1) of the antimalarial agents febrifugine (d-1) was synthesized using an stereoselective Michael reaction of an omega-amidoenone (5) which was prepared by the Wittig reaction of piperidinediol (7).     

DNA damage by fasicularin

Fasicularin is a structurally novel thiocyanate-containing alkaloid isolated from the ascidian Nephteis fasicularis. Early biological experiments suggested that this compound's cytotoxic properties may stem from its ability to damage cellular DNA. Sequence gel analysis reveals that treatment of a 5'-32P-labeled DNA duplex with fasicularin in pH 7.0 buffer causes strand cleavage selectively at guanine residues. Further experiments indicate that production of these base-labile lesions in DNA involves alkylation of guanine residues by a fasicularin-derived aziridinium ion. This work reveals fasicularin as the first natural product found to generate a DNA-alkylating aziridinium ion via a mechanism analogous to the clinically used anticancer drugs mechlorethamine, melphalan, and chlorambucil.     

The functional layered organosilica materials prepared with anion surfactant templates

A novel strategy for the synthesis of layered organosilica is demonstrated. The ionic interaction between the anionic group of a surfactant (sodium dodecyl sulfate) and the cationic organic group of an organosilane (3-aminopropyltrimethoxysilane, ATMS) under acidic conditions was utilized to create a layered organosilica at room temperature. The inorganic part of the organosilica layer was an Si-O hexagonal sheet, and organofunctional groups were alternately arranged on both sides of the sheet. The layered structure of the ATMS organosilica was retained after the removal of the surfactant with chloride anion. The properties of the layered ATMS organosilica were investigated. The layered ATMS-Cl organosilica is stable and possesses a definite layer structure in water or ethanol. Various kinds of anions can be intercalated in the interlayer space of the layered ATMS organosilicas and the layer was expanded dependent on the intercalated anions. The structure of the layered ATMS organosilica was well retained during the intercalation processes.     

A missing allene of heavy Group 14 elements: 2-germadisilaallene

The first stable 2-germadisilaallene was synthesized by the reduction of a 2 ratio 1 mixture of a stable dialkylsilylene and dichlorogermylene-dioxane complex with KC8; the 2-germadisilaallene showed dynamic disorder similar to the corresponding trisilaallene in the solid state.     

On the breaking of chiral symmetry in the Schwinger model

The Schwinger model is reinvestigated in the A₁ = 0 gauge. Based on the explicit operator solution, it is suggested that the breaking of chiral symmetry is dynamical and the vacuum is unique contrary to the arguments by Kogut and Susskind.     

Experimentelle Best?tigung der modernen Theorie der Molekulargewichtsfraktionierung auf Grund der L?slichkeitsunterschiede

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