title: Independent pathway formation of guest-host in host ternary complexes made of ammonium salt, calixarene, and cyclodextrin.
abstract: The interaction between γ-cyclodextrin and amphiphilic p-sulfonatocalix[4]arenes was studied using NMR and isothermal titration calorimetry techniques. The results indicate that these calixarenes are able to form 1:1, 1:2, and 2:1 host-guest complexes with the cyclodextrin. The ROESY spectra suggest that the cyclodextrin binds the calixarenes through the hydrophobic alkyl chains. p-Sulfonatocalix[4]arenes, which are traditionally used as host molecules, act as guests in the presence of γ-cyclodextrin. However, their recognition site remains active upon complexation with the cyclodextrin, and ternary complexes can be devised. Here, we also demonstrate the formation of such complexes using tetramethylammonium chloride as a model guest. Moreover, it is also demonstrated that the recognition properties of the calixarene are unaffected upon complexation with the cyclodextrin.
authors.affiliation: Departamento Quimica Fisica, Centro Singular de Investigación en Química Biológica y Materiales Moleculares, Universidad de Santiago, 15782 Santiago, Spain.
authors.forename: Nuno
authors.initials: N
authors.lastname: Basílio
authors.forename: Vitor
authors.initials: V
authors.lastname: Francisco
authors.forename: Luis
authors.initials: L
authors.lastname: García-Río