| Autor: |
Ayling AJ; School of Chemistry, University of Bristol Cantock's Close, Bristol, UK., Broderick S, Clare JP, Davis AP, Pérez-Payán MN, Lahtinen M, Nissinen MJ, Rissanen K |
| Jazyk: |
angličtina |
| Zdroj: |
Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2002 May 03; Vol. 8 (9), pp. 2197-203. |
| DOI: |
10.1002/1521-3765(20020503)8:9<2197::AID-CHEM2197>3.0.CO;2-J |
| Abstrakt: |
The extraction-based protocol for measuring binding constants, developed by Cram and co-workers, has been extended for use with anionic substrates. The method is especially useful for high-affinity receptors, allowing very high binding constants to be measured in nonpolar solvents. Distribution constants K(d) between chloroform and water have been obtained for tetraethylammonium chloride and bromide, thus calibrating the method for these two substrates. Application to steroidal podands 5-9 has confirmed the ability of electron-withdrawing groups to enhance hydrogen-bond donor capabilities. Binding constants of approximately 3 x 10(7) M(-1) have been measured for the most powerful receptor 7. An X-ray crystal structure of 15, the methyl ester analogue of 7, reveals a well-defined binding site preorganised for anion recognition. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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