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The separation and detection of small oligopeptides in CE with contactless conductivity detection were demonstrated. A strongly acidic separation buffer (0.5 M acetic acid) was employed in order to render the species cationic. Separation of the stereoisomers was achieved in typically 10-15 min by using either dimethyl-beta-CD (DM-beta-CD), (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (18C(6)H(4)), a combination of the two substances, or of histidine, as buffer additives. Calibration curves were determined for isomers of Gly-Asp and H-Pro-Asp-NH(2), in the range of 0.05-0.5 mM and 0.1-1 mM, respectively, and were found to be linear. LODs were determined to be in the order of 1.0 microM. The determination of isomeric impurities down to about 1% was found possible. Species showing good separation could also be successfully determined on an electrophoretic lab-on-chip device, with analysis times of a few minutes.

An 'azido gauche effect' determines the conformation of (4S)-and (4R)-azidoproline (Azp) derivatives and affects the s-cis:s-trans conformer ratio of Xaa-Azp bonds. The article summarizes our research on the conformational analysis of monomers as well as oligomers derived from (4S)Azp and (4R)Azp. We show that (4S)Azp and (4R)Azp can be used to tune the stability of the polyproline II (PPII) helix. In addition we demonstrate that Azp containing oligoprolines are attractive molecular scaffolds with a well-defined helical conformation that can be readily further functionalized using e.g. click chemistry.

Within the present work, synthesis and properties of three stereoisomeric hybrid materials consisting of a πconjugated oligothiophene backbone and a single amino acid (proline), which is attached by click chemistry, are described. The hybrids were in particular investigated regarding their self-assembling behavior in solution. From optical investigations, including circular dichroism spectroscopy, the formation of chiral suprastructures could be deduced and correlated with the stereochemistry of the proline residue. In addition, an elaborate theoretical model of the compounds' self-assembly into suprastructures was developed on the basis of the experimental findings.

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