title: Controlling the conformation and interplay of p-sulfonatocalix[6]arene as lanthanide crown ether complexes.
abstract: Control over the conformational flexibility of p-sulfonatocalix[6]arene in the solid state is possible in the presence of varied stoichiometric amounts of [18]crown-6 and selected lanthanide(III) chlorides. Complexes 1 and 2 have the calixarene in the elusive up-up double cone conformation, whilst complex 3 has the calixarene in the centrosymmetric up-down double partial cone conformation, whereby it acts as a divergent receptor. Complex 1 has a double molecular capsule arrangement which is composed of two p-sulfonatocalix[6]arenes shrouding two [18]crown-6 molecules, also with both coordinated and homoleptic aquated lanthanide ions around the hydrophilic sulfonate rims of the calixarenes. Complex 2 has a ferris wheel arrangement with one lanthanide metal centre coordinated to a sulfonate group and another coordinated to the crown ether whilst tethered to a sulfonate group of the calixarene. Complex 3 forms from a solution with large excess of [18]crown-6, and possesses a crown ether molecule in each of the partial cones and has homoleptic aquated lanthanide ions involved in a complicated hydrogen-bonding regime within the extended structure.
authors.affiliation: Department of Chemistry, Univeristy of Leeds, UK.
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Dalgarno
authors.forename: Michaele J
authors.initials: MJ
authors.lastname: Hardie
authors.forename: Mohamed
authors.initials: M
authors.lastname: Makha
authors.forename: Colin L
authors.initials: CL
authors.lastname: Raston