A short synthetic route is outlined, starting from bromo-BN derivatives, via halogen lithium exchange, subsequent Michael reaction with dimethylaminoacrolein, hydrolysis to the corresponding aldehyde, and final condensation with a benzothiazolium unit to produce a BN-pentamethinium system, which absorbs in the visible range around 450 nm. Enantiopure ligands show a decent Cotton effect in the CD spectrum. Preliminary data show potential of these compounds in the area of supramolecular chemistry (enantioselective recognition) and also for medicinal application (induction of apoptosis). [reaction: see text]

• MeSH
• apoptóza účinky léků   MeSH
• bromované uhlovodíky chemie   MeSH
• cirkulární dichroismus MeSH
• katalýza MeSH
• molekulární struktura MeSH
• naftaleny chemická syntéza   chemie   MeSH
• stereoizomerie MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bromované uhlovodíky MeSH
• naftaleny MeSH

A new ion-exchanger type chiral stationary phase for high-performance liquid chromatography was prepared. The synthetic protocol is based on derivatization of silica with (3-iodopropyl)trimethoxysilane in the first step followed by immobilization of strychnine via quaternization of nitrogen atom of the alkaloid strychnine. The synthesized chiral stationary phase was chromatographically characterized. The main effort was headed towards the evaluation of the enantioselectivity of the novel sorbent. For that purpose a set of suitable chiral probes, specifically, binaphthyl derivatives, was employed. The influence of methanol content, concentration of aqueous ammonium acetate buffer, and its pH on retention factors, separation selectivity, and resolution of the atropoisomers of the mentioned chiral solutes was studied in detail. It was demonstrated that the new chiral stationary phase was capable to separate atropoisomers of four out of seven testing compounds. Despite the strong influence of the above mentioned variables on retention, their impact on selectivity and resolution was rather moderate. Concerning retention mechanism, it seems that electrostatic interaction between the positively charged quaternary nitrogen of the chiral stationary phase and anionic solute participates significantly in the retention process.

• Klíčová slova
• Alkaloid, Binaphthyl derivatives, Chiral separation, Chiral stationary phase, Strychnine,
• MeSH
• acetáty chemie   MeSH
• methanol chemie   MeSH
• stereoizomerie MeSH
• strychnin chemie   MeSH
• vysokoúčinná kapalinová chromatografie přístrojové vybavení   metody   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• acetáty MeSH
• ammonium acetate MeSH Prohlížeč
• methanol MeSH
• strychnin MeSH

Retention and enantioseparation behavior of ten 2,2'-disubstituted or 2,3,2'-trisubstituted 1,1'-binaphthyls and 8,3'-disubstituted 1,2'-binaphthyls, which are used as catalysts in asymmetric synthesis, was investigated on eight chiral stationary phases (CSPs) based on beta-CD, polysaccharides (tris(3,5-dimethylphenylcarbamate) cellulose or amylose CSPs) and new synthetic polymers (trans-1,2-diamino-cyclohexane, trans-1,2-diphenylethylenediamine and trans-9,10-dihydro-9,10-ethanoanthracene-(11S,12S)-11,12-dicarboxylic acid CSPs). Normal-, reversed-phase and polar-organic separation modes were employed. The effect of the mobile phase composition was examined. The enantiomeric separation of binaphthyl derivatives, which possess quite similar structures, was possible in different enantioselective environments. The substituents and their positions on the binaphthyl skeleton affect their properties and, as a consequence, the separation system suitable for their enantioseparation. In general, the presence of ionizable groups on the binaphthyl skeleton, substitution with non-identical groups and a chiral axis in the 1,2' position had the greatest impact on the enantiomeric discrimination. The 8,3'-disubstituted 1,2'-binaphthyl derivatives were the most easily separated compounds in several separation systems. From all the chiral stationary phases tested, cellulose-based columns were shown to be the most convenient for enantioseparation of the studied analytes. However, the polymeric CSPs with their complementary behavior provided good enantioselective environments for some derivatives that could be hardly separated in any other chromatographic system.

• MeSH
• beta-cyklodextriny chemie   MeSH
• naftaleny chemie   izolace a purifikace   MeSH
• polymery chemie   MeSH
• polysacharidy chemie   MeSH
• stereoizomerie MeSH
• vysokoúčinná kapalinová chromatografie metody   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• beta-cyklodextriny MeSH
• betadex MeSH Prohlížeč
• naftaleny MeSH
• polymery MeSH
• polysacharidy MeSH

Cyclofructans and preferentially their derivatives can serve as chiral selectors for the separation of different enantiomers/atropisomers. Moreover, the strong ionophoric nature of the 18-crown-6 ether core of cyclofructan 6 for barium cations may be exploited to enhance or modify enantioselectivity. In this work isopropyl-cyclofructan-6 was used as a chiral selector for the separation of binaphthyl atropisomers in HPLC and CE. The data from both separation systems were compared with each other. While in HPLC the chiral selector was bonded to silica gel to afford a chiral stationary phase, in capillary electrophoresis it was freely mobile in the background electrolytes (BGE). This significant difference is reflected in the separation potential of the two separation systems. All five analytes could be baseline separated in HPLC (reversed phase mode) while only one derivative was baseline resolved in CE. This result was attributed to the more rigid nature of the immobilized chiral selector. Addition of Ba(2+) to the mobile phase or BGE improved chiral separations in both systems. The results may help to elucidate the interaction mechanism in these systems with cyclofructan derivatives and to gain some general knowledge of their separation potential.

• Klíčová slova
• Atropisomer, Capillary electrophoresis, Chiral separation, Cyclofructan, High performance liquid chromatography, Isopropyl-cyclocfructan-6,
• MeSH
• chromatografie s reverzní fází metody   MeSH
• elektroforéza kapilární metody   MeSH
• elektrolyty MeSH
• fruktany analýza   chemie   MeSH
• stereoizomerie MeSH
• vysokoúčinná kapalinová chromatografie metody   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cyclofructan 6 MeSH Prohlížeč
• elektrolyty MeSH
• fruktany MeSH

Vibrational (VCD), electronic circular dichroism (ECD), and IR absorption spectra together with transparent spectral region optical rotation (OR) of two derivatives of bisphenylene 1,1'-binaphthyl-based phosphoramidites containing three stereogenic axes were measured and the results were compared with simulated data obtained by ab initio calculations with density functional theory. An excellent agreement between experimental and predicted B3LYP/6-31G** and BPW91/6-31G** VCD spectra enabled the assignment of all VCD bands in the experimental spectra, while the Gibbs free energy of all the conformers allowed the determination of their relative populations. The calculation of ECD spectra showed that CAM-B3LYP/6-311G** provided results superior to those of B3LYP/6-311G**. The theoretical results for the OR at the B3LYP/6-311G** and CAM-B3LYP/6-311G** levels were in good agreement with experimental optical rotations, but exhibited lower sensitivity in determining particular conformers than VCD and ECD. By a careful comparison of experimental VCD, IR, and ECD spectra and OR with calculated data, it was possible to assign the absolute configuration of all three stereogenic axes and to determine the molecular structure of the studied bisphenylene 1,1'-binaphthyl-based phosphoramidites in solution with a high degree of confidence.

• Publikační typ
• časopisecké články MeSH