Tünde Tóth

New highly lipophilic enantiopure crown ethers containing a heterocyclic unit have been synthesized. Phase transport, UV-Vis- and fluorescence spectrophotometric investigations as well as electrochemical studies on the complexation of the new macrocycles with several amine and amino acid derivatives were also carried out. Achiral amines were used for studying the structural preference of the new macrocycles. Among the studied structural features of the guest molecules, the intermolecular π-π interaction showed the most significant effect on complexation, which made the aralkylamine-type compounds the most preferable guest molecules. The studied liquid membrane-based applications and photophysical investigations showed appreciable enantiomeric recognition toward some aralkylamine model compounds with homochiral preferences. New crown ether derivatives (R,R)-2 and (S,S)-2 were successfully applied as enantioselective carrier and sensor molecules.

New enantiopure dimethyl‐substituted acridino‐18‐crown‐6 and acridino‐21‐crown‐7 ethers containing a carboxyl group at position 9 of the acridine ring [(S,S)‐8, (S,S)‐9, (R,R)‐10] were synthesized. The pK_a values of the new crown ethers [(S,S)‐8, (S,S)‐9, (R,R)‐10] and of an earlier reported macrocycle [(R,R)‐2] were determined by UV‐pH titrations. Crown ether (S,S)‐8 was attached to silica gel by covalent bonds and the enantiomeric separation ability of the newly prepared chiral stationary phase [(S,S)‐CSP‐12] was studied by high‐performance liquid chromatography (HPLC). Homochiral preference was observed and the best separation was achieved for the enantiomers of 1‐NEA. Ligands (S,S)‐9 and (R,R)‐10 are precursors of enantioselective sensor and selector molecules for the enantiomers of protonated primary amines, amino acids, and their derivatives.

Certain bactericidal antibiotics target mitochondrial components and, due to the leakage of electrons from the electron transport chain, one-electron reduction might occur that can lead to intermediates passing the electron to suitable acceptors. This study aimed at investigating the one-electron reduction mechanism of selected penicillin derivatives using pulse radiolysis techniques. Penicillins can accommodate the electron on each of their carbonyl carbon. Ketyl radicals are thus produced, which are reducing agents with possibility to interact with suitable biomolecules. A detailed mechanism of the reduction is reported.