Silver compounds in synthetic chemistry. Part 3. 4-Tetrafluoropyridyl silver(I), AgC5F4N - A reagent for redox transmetallations with group 12-14 elements

4-Tetrafluoropyridyl silver(I), AgC₅F₄N, has been obtained from Me₃SiC₅F₄N and AgF in nearly quantitative yield. Reactions with bis(triphenylphosphoranyliden)ammonium chloride, [PNP]Cl, gave crystalline material of the composition [PNP][Ag(C₅F₄N)₂]. Redox transmetallations of AgC₅F₄N and group 12-14 elements Zn, Cd, Hg, Ga, In, Sn yielded the corresponding 4-tetrafluoropyridyl element compounds. The molecular structures of [PNP][Ag(C₅F₄N)₂], Hg(C₅F₄N)₂, Ga(C₅F₄N)₃ · EtCN · H₂O, In(C₅F₄N)₃ · 2EtCN and Sn(C₅F₄N)₄ are discussed.     

A new molecular fluorescence depolarization effect: The coherence decay time of NO2

Measurements of the coherence decay of NO₂ by zero magnetic field level crossing (Hanle effect) reveal a novel depolarization effect of the fluorescence light not known from similar experiments on atoms and diatomic molecules.     

Stereospezifische Synthese von 6β,7β-Methylen-20-spirox-4-en-3,21-dion (Prorenon). Über Steroide. 235. Mitteilung

Stereospecific synthesis of 6β,7β-methylene-20-spirox-4-ene-3,21-dione A stereospecific synthesis of the highly active 6β,7β-methylene-20-spirolactone 4 (Prorenone) is described.     

High-performance liquid chromatographic separation of human haemoglobins. Simultaneous quantitation of foetal and glycated haemoglobins

A high-performance liquid chromatographic system, which uses a weak cation exchanger (PolyCATA) together with Bis-Tris buffer (pH 6.47-7.0) and sodium acetate gradients, is described. Samples from adults and newborns were analysed and a clean separation of many minor and major normal and abnormal haemoglobin (Hb) variants was greatly improved. The method allows the separation of minor foetal haemoglobin (HbF) variants and the simultaneous quantitation of HbF and glycated HbA. HbF values correlated well with those obtained by the alkali denaturation method (r = 0.997). The glycated haemoglobin (HbAIc) levels measured in patients with high HbF concentrations correlated with the total glycated haemoglobin determined by bioaffinity chromatography (r = 0.973). The procedure is useful for diagnostic applications and affords an effective and sensitive way of examining blood samples for haemoglobin abnormalities.     

Über rote farbstoffe, die sich vom 2-phenyl-imidazolon-4(5) ableiten

Aqueous solutions of glycyl-benzoyl-imide (I) become dark red on standing for several days or on heating. The red pigments are formed via 2-phenyl-imidazolone-4(5) (II), which can be trapped by reaction with benzaldehyde. Paper electrophoresis using a special buffer system enabled comparison with other red products described in the literature or synthetized otherwise by us. None of them proved to be identical with the “glyoxaline red” of Ruhemann and Stapleton.