Thermodynamic and NMR Studies of Solvent Effect on Enantiomeric Recognition for a Chiral Organiz Ammonium Cation by Chiral Diketopyridino-18- Crown-6 Type Ligands at 25.0 deg C.
BRIGHAM YOUNG UNIV PROVO UT DEPT OF CHEMISTRY
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Three chiral diketopyridino-18-crown-6 type macrocycles have been shown to exhibit a high degree of enantiomeric recognition toward alpha-1- naphthylethylammonium perchlorate NapEt in various ratios of chloroform methanol CDCl3CD3OD and 1,2-dichloroethanemethanol C2H4Cl2CH3OH solvent mixtures from 100 to 10 methanol component. In most cases differences in log K values deltalog K for R- and S-NapEt complexation with the chiral macrocycles are larger than 0.5. The degree of the enantiomeric recognition indicated by the deltalog K value changes noticeably with the binary solvent components. The recognition is better in the solvents having a moderate methanol component than in the binary solvents having either a high a low methanol component. The highest degree of recognition is observed in 64 vv CDCl3 CD3OD and C2H4Cl2CH3OH solvent mixtures and in a 73 vv C2H4Cl2CH3OH mixture for chiral S,S-1 macrocycle. Author
- Inorganic Chemistry
- Organic Chemistry
- Physical Chemistry
- Atomic and Molecular Physics and Spectroscopy