| Abstract
| - A cationic chiral cyclophane was synthesized and studied as a host for chiral and racemic π-donormolecules. The cyclophane host has a rigid binding cavity flanked by (S)-(valine-leucine-alanine)and N,N‘-dibenzyl-4,4‘-bipyridinium subunits, which allow for hydrogen-bonding and π-stackinginteractions with included aromatic guest molecules. 1H NMR binding titrations were performedwith several different pharmaceutically interesting guest molecules including β-blockers, NSAIDs,and amino acids and amino acid derivatives. The host−guest complexation constants were generallysmall for neutral and cationic guests (0−39 M-1 at 20 °C in water/acetone mixtures). However, a(R)/(S) enantioselectivity ratio of 13 ± 5 was found for DOPA, a strongly π-donating cationic guest.Two-dimensional NOESY 1H NMR spectra confirm that (R)-DOPA binds inside the cavity of thehost and that there is no measurable interaction of the cavity with (S)-DOPA under the sameconditions.
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