title: Ion pair cooperative binding of potassium salts by new rhenium(I) bipyridine crown ether receptors.
abstract: The new rhenium(I) bipyridine crown ether receptors 1-4 have been prepared and their ion pair recognition properties examined. The crystal structure of [1.KCl](2).2H(2)O demonstrates that potassium is coordinated by benzo-18-crown-6 and chloride is hydrogen bonded to the amide groups. Receptor 3 extracts solid KCl and KOAc into chloroform via ion pair complexation. NMR and emission titration studies with receptors 1-4 and KCl/KOAc show that cobound potassium enhances anion binding strength by electrostatic and conformational effects. Significant cooperative interactions are observed between the anion and cation sites for host 4 in CH(3)CN. This molecule coordinates potassium to form a 1:1 intramolecular sandwich complex, which preorganizes the host for acetate binding.
authors.affiliation: Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, UK.
authors.forename: L H
authors.initials: LH
authors.lastname: Uppadine
authors.forename: J E
authors.initials: JE
authors.lastname: Redman
authors.forename: S W
authors.initials: SW
authors.lastname: Dent
authors.forename: M G
authors.initials: MG
authors.lastname: Drew
authors.forename: P D
authors.initials: PD
authors.lastname: Beer
mesh_terms: D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives*; D000085:Acetates / Q000737:chemistry; D000838:Anions / Q000737:chemistry; D002414:Cations, Monovalent / Q000737:chemistry; D018360:Crystallography, X-Ray; D004988:Ethers, Cyclic / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011189:Potassium Chloride / Q000737:chemistry*; D012211:Rhenium / Q000737:chemistry*; D016339:Spectrometry, Mass, Fast Atom Bombardment
chemical_list: D000085:Acetates; D000838:Anions; D002414:Cations, Monovalent; D004988:Ethers, Cyclic; D009942:Organometallic Compounds; D015082:2,2'-Dipyridyl; D011189:Potassium Chloride; D012211:Rhenium