title: Potassium selective calix[4]semitubes.
abstract: A new class of ionophore consisting of two calix[4]arene units linked through the lower rim by two ethylene chains, in combination with propyl ether and phenolic functional groups, has been developed. These calix[4]semitube molecules exhibit remarkable selectivity and fast complexation kinetics for potassium over all Group 1 metal cations. Molecular modelling studies, using structural models derived from crystallographic data, suggest the potassium cation is complexed by a horizontal, side-on route and not through the calix[4]arene annulus. The length of the bridging alkylene chain between the respective calix[4]arenes of the semitube structure dictates the strength and selectivity of alkali metal cation binding.
authors.affiliation: Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, UK.
authors.forename: Philip R A
authors.initials: PR
authors.lastname: Webber
authors.forename: Andrew
authors.initials: A
authors.lastname: Cowley
authors.forename: Michael G B
authors.initials: MG
authors.lastname: Drew
authors.forename: Paul D
authors.initials: PD
authors.lastname: Beer
mesh_terms: D047250:Calixarenes; D018360:Crystallography, X-Ray; D007476:Ionophores / Q000138:chemical synthesis / Q000737:chemistry*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008672:Metals, Alkali / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D010636:Phenols / Q000138:chemical synthesis / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D007476:Ionophores; D008672:Metals, Alkali; D010636:Phenols; C121325:calix(4)arene; D047250:Calixarenes; D011188:Potassium