title: Water-soluble molecular capsule for the complexation of cesium and thallium cations.
abstract: Binding properties of cesium and thallium cations by an enantiopure cryptophane derivative PP-1 have been investigated in water under basic conditions. The binding process has been evidenced using electronic circular dichroism (ECD), and binding constants of the Cs(+)@PP-1 and Tl(+)@PP-1 complexes have been determined from isothermal titration calorimetry (ITC) experiments in LiOH/H(2)O, NaOH/H(2)O, and KOH/H(2)O solutions. In addition, Tl(+)@PP-1 complex has been characterized for the first time by (205)Tl NMR spectroscopy. Cryptophane 1 exhibits an exceptionally high affinity for thallium and cesium cations in a large range of experimental conditions (nature, concentration of the counterion, and temperature). For example, binding constants as high as 2.9 × 10(9) M(-1) and 5.3 × 10(8) M(-1) have been measured by ITC at 298 K in NaOH/H(2)O (0.1 M) solution, for the Tl(+)@PP-1 and Cs(+)@PP-1 complexes, respectively. The high affinity of cryptophane 1 for Cs(+) and Tl(+) cations is preserved at higher LiOH, NaOH, and KOH concentrations and under extreme basic conditions, revealing the stability and the great selectivity of this supramolecular system toward Li(+), Na(+), and K(+) cations.
authors.affiliation: Laboratoire de Chimie de l'ENS Lyon (UMR 5182-CNRS), École Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon, France. thierry.brotin@ens-lyon.fr
authors.forename: Thierry
authors.initials: T
authors.lastname: Brotin
authors.forename: Dominique
authors.initials: D
authors.lastname: Cavagnat
authors.forename: Patrick
authors.initials: P
authors.lastname: Berthault
authors.forename: Roland
authors.initials: R
authors.lastname: Montserret
authors.forename: Thierry
authors.initials: T
authors.lastname: Buffeteau
mesh_terms: D002151:Calorimetry; D002412:Cations / Q000737:chemistry; D002586:Cesium / Q000737:chemistry*; D002942:Circular Dichroism; D056831:Coordination Complexes / Q000737:chemistry; D011083:Polycyclic Compounds / Q000138:chemical synthesis / Q000737:chemistry; D013237:Stereoisomerism; D013793:Thallium / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D002412:Cations; D056831:Coordination Complexes; D011083:Polycyclic Compounds; C523242:cryptophane; D014867:Water; D002586:Cesium; D013793:Thallium