Synthesis, Structure and Selective Upper Rim Functionalization of Long Chained Alkoxythiacalix[4]arenes

The synthesis and X-ray structure investigation of the cone shaped monodecyloxythiacalix[4]arene, as well as the introduction of the reactive bromide or chloromethyl groups on it’s upper rim are described. Preparation of the amphiphilic derivative of thiacalixarene bearing three hydrophilic diethoxyphosphoryl groups at the upper rim and lipophilic decyloxy group at the lower rim is presented.     

Hexafluoroacetone as a Protecting and Activating Reagent. Regioselective Esterification of Aspartic, Malic, and Thiomalic Acid

Summary. Hexafluoroacetone reacts with -functionalized ,-dicarboxy acids like aspartic, malic, and thiomalic acid to give exclusively five-membered lactones. The -carboxylic groups remain unaffected and can be derivatized separately. They can be linked i.a. to orthogonal protecting groups or multivalent alcohols like pentaerythritol to give synthetically valuable building blocks.     

Complexation de l'argent(I) par des teramines cycliques

Complexation of Silver(I) by Cyclic Tetramines The nature of Ag(I)-complexes with 1,4,8,11-tetraazacyclotetradecane ( 1 ), 1,5,9,13-tetraazacyclohexadecane ( 2 ) 1,5,10,14-tetraazacyclooctadencane ( 3 ) and 1,6,11,16-tetraazacycloeicosane ( 4 ) is studied. The effect of ring size on disproportionation of the Ag() cation in the presence of ligand is reported. The stability of Ag(I)-complexes with 3 and 4 in aqueous solution is determined by means of potentiometric titration.     

Untersuchung pharmazeutischer Pr?parate

Ohne Zusammenfassung     

Der Bestimmung von Hydroxylgruppen mit Grignard-Reagens

Ohne Zusammenfassung     

Adsorption of plasmid DNA on ceramic hydroxyapatite chromatographic materials

The adsorption of plasmid DNA onto two different types of ceramic hydroxyapatite beads with a particle diameter of 20 μm, namely Ceramic Hydroxyapatite Type II and the Type III, which is not commercially available, were investigated. Type II and the Type III have a pore diameter of 80 and 240 nm, respectively. Equilibrium and dynamic binding capacity for a 4.9 kbp model plasmid on Ceramic Hydroxyapatite Type II and Type III were enhanced by addition of NaCl to the adsorption buffer. This result indicates that the adsorption mechanism cannot be solely explained by electrostatic interaction. The affinities of plasmid DNA for Ceramic Hydroxyapatite Type II (with a K(D) of ≈0.005 mg/mL) and to Hydroxyapatite Type III (with a K(D) of ≈0.045 mg/mL) were not affected by NaCl, whereas the binding capacity was. This observation corroborates the assumption that a change of the shape of the plasmid molecule is affected and could be the reason for increased binding capacity with salt. The maximal binding capacity shows that at least a part of the CHT II bead must be accessible for the plasmid, whereas CHT III can be saturated with the plasmid. In both cases, an extremely hindered transport takes place.