Configurational conditions and digraphs

Configurational conditions (Schließungsaussagen) of a noncommutative space will be developped from pairs (, ) of digraphs where is a partial digraph of . In this way we obtain an extensive generalization of Pfalzgraf 's q-simplex-conditions Sim_q.In Memoriam Hans Zassenhaus     

Aminoalkoholester von Hydroxyboranen,IX Salicylamid-Bor-Mannichbasen als potentielle Antitumorwirkstoffe

A synthesis of new boron containingMannich bases of salicylamide by reaction of salicylamide, formaldehyde and boron-heterocycles is reported.

VIII. Mitteilung:Stump, R. K., Zimmerman jr., H. K., Schleppnik, A. A., Gutsche, C. D., Liebigs Ann. Chem.667, 18 (1963).     

Einsatz des Spiegel-Elektronenmikroskops zur Untersuchung dielektrischer dünner Schichten

A technique for imaging of charge inhomogeneities in dielectric layers with the aid of the mirror electron microscope is described. The experimental results given being interpreted in a semiquantitative way, are first of all related to silicon oxide evaporation layers.     

Dynamic kinetic resolution of transient hemiketals: a strategy for the desymmetrisation of prochiral oxetanols

Identification of an electron poor trifluoroacetophenone allows the formation of uniquely stable hemiketals from prochiral oxetanols. When exposed to a cobalt(ii) catalyst, efficient ring-opening to densely functionalized dioxolanes is observed. Mechanistic studies suggest an unprecedented redox process between the cobalt(ii) catalyst and the hemiketal that initiates the oxetane-opening. Based on this observation, a dynamic kinetic resolution of the transient hemiketals is explored that uses a Katsuki-type ligand for stereoinduction (up to 99 : 1 dr and 96 : 4 er) and allows a variety of 1,3-dioxolanes to be accessed (20 examples up to 98% yield).

Desymmetrization of prochiral oxetanols via an electron-deficient hemiketal intermediate is achieved. Key to this process is the catalyst''s chiral recognition of one of the two hemiketal enantiomers enabling an efficient dynamic kinetic resolution.     

Separation of Dihydro-Isocoumarins and Dihydro-Stilbenoids from Hydrangea macrophylla ssp. serrata by Use of Counter-Current Chromatography

Previously, different Hydrangea macrophylla ssp. serrata cultivars were investigated by untargeted LC-MS analysis. From this, a list of tentatively identified and unknown compounds that differ significantly between these cultivars was obtained. Due to the lack of reference compounds, especially for dihydro-isocoumarins, we aimed to isolate and structurally characterise these compounds from the cultivar ‘Yae-no-amacha’ using NMR and LC-MS methods. For purification and isolation, counter-current chromatography was used in combination with reversed-phase preparative HPLC as an orthogonal and enhanced purification workflow. Thirteen dihydro-isocoumarins in combination with other metabolites could be isolated and structurally identified. Particularly interesting was the clarification of dihydrostilbenoid glycosides, which were described for the first time in H. macrophylla ssp. serrata. These results will help us in further studies on the biological interpretation of our data.     

Zur Defokussierungsabhängigkeit der elektronenmikroskopischen Netzebenenabbildung

The defocusing dependence of the lattice plane image contrast in the region of interplanar spacings between 8 Å and 1.4 Å is investigated experimentally and interpreted theoretically using calculated phase contrast transfer characteristics. On the one hand, it is well-known that in the case of coaxial illumination optimum image contrast is obtained if using suitable underfocus, on the other hand, contradictory statements exist for the conditions of contrast formation if using tilted illumination. In the present paper it is shown that in this case optimum contrast is attained with an appropriate overfocus. A possible explanation is given which takes into account the influence of the deviation from the exact symmetrically tilted illumination.     

On the interaction of different types of ligands binding to the same molecule Part II: systems with n to 2 and n to 3 binding sites

In the first part of this work we formulated the decoupled sites representation for two different types of ligands and highlighted special properties of the case of n binding sites for ligand L ₁ and one binding site for ligand L ₂. Moreover, for this case, we identified the microstate constants as unique components all decoupled molecules share. In the second part on hand, we investigate the cases with (n, 2) and (n, 3) binding sites. As it is difficult to solve the system of equations occurring when a molecule with more than one binding site for both ligands shall be decoupled, we present applicable calculation methods which exploit the special structure of the system of equations. Moreover, we investigate which unique properties all decoupled molecules share and show that for two different decoupled molecules with the same binding polynomial, not all microstate constants of a certain macrostate are permutations of the microstate constants of the other molecule.