title: Cationic acyclic cucurbit[n]uril-type containers: synthesis and molecular recognition toward nucleotides.
abstract: We report the synthesis ofM2NH3which is a tetracationic analogue of our prototypical acyclic CB[n]-type molecular containerM2. BothM1NH3andM2NH3possess excellent solubility in D2O and do not undergo intermolecular self-association processes that would impinge on their molecular recognition properties. CompoundsM1NH3andM2NH3do, however, undergo an intramolecular self-complexation process driven by ion-dipole interactions between the ureidyl C=O portals and the OCH2CH2NH3arms along with inclusion of one aromatic wall in its own hydrophobic cavity. The Kavalues forM1NH3andM2NH3toward seven nucleotides were determined by1H NMR titration and found to be quite modest (Kain the 102- 103M-1range) althoughM2NH3is slightly more potent. The more highly charged guests (e.g. ATP) form stronger complexes withM1NH3andM2NH3than the less highly charged guest (e.g. ADP, AMP). The work highlights the dominant influence of the ureidyl C=O portals on the molecular recognition behavior of acyclic CB[n]-type receptors and suggests routes (e.g. more highly charged arms) to enhance their recognition behavior toward anions.
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.
authors.forename: David
authors.initials: D
authors.lastname: Sigwalt
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.
authors.forename: Peter Y
authors.initials: PY
authors.lastname: Zavalij
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.
authors.forename: Lyle
authors.initials: L
authors.lastname: Isaacs