Abstract (eng)
The present diploma thesis aims at presenting a new class of chiral selectors, phosphonic acid pseudo-peptides, for enantiomer separation in capillary electrochromatography (CEC), as well as their synthesis.
The biomimetics herein were prepared in an Ugi reaction, a multicomponent reaction which was found to be suitable for the generation of whole compound libraries in a short time. The primary test compound was methyl 3,3-dimethyl-2-[4-allyloxy-α-(2,6-dimethylanilido)-benzylamino]-butane phosphonate, a novel zwitter-ionic pseudo-peptide. Preliminary experiments were performed to choose the best support and to explore immobilization chemistry. Concerning the support, silica monoliths were provided by Merck and organic polymer monoliths (OPMs) were produced in-house.
The OPMs as well as the silica monoliths revealed epoxy groups at their surfaces, which can be thiolized and subsequently subjected to radical addition of a selector. Immobilization chemistry via thiolization from epoxy groups had been investigated on OPMs before, but was tested for the first time on silica monoliths. For this reason, preliminary experiments evaluating the adoption of this immobilization technique for silica monoliths and comparing the performance to OPMs were carried out.
tert-Butylcarbamoylquinidine was employed as chromatographic test selector in CEC. Better separation results were obtained with silica monolithic support, which could successfully be employed for the separation of aryloxy carboxylic acid herbicides (amongst others Mecoprop and Dichlorprop) that could not be separated on the OPM.
Subsequently, a silica monolith was used for the immobilization of enantiopure methyl 3,3-dimethyl-2-[4-allyloxy-α-(2,6-dimethylanilido)-benzylamino]-butane phosphonate. The enantiomers of Clenbuterol, a β2-sympathomimeticum, could successfully be baseline-separated, indicating the potential of phosphonic acid pseudo-peptide selectors.