HOST-GUEST INTERACTIONS IN AQUEOUS-MEDIA WITH P-TERT-BUTYLCALIX[4]ARENE BEARING POLYOXYETHYLENE CHAINS

The interactions of p-tert.-butylcalix[4]arene bearing polyoxyethylene chains (C3) with pyrene (Py), 1-anilino-8-naphthalenesulfonate (ANS) and N-phenyl-naphthylamine (NPN) in aqueous solution were studied by absorption and fluorescence measurements. Absorption spectral changes and fluorescence enhancements reveal that C3, which has a hydrophobic cavity, can include organic molecules and ions in aqueous solution and form 1 : 1 host-guest complexes with ANS and NPN. C3 forms inclusion complexes with Py at different stoichiometries depending on the host : guest molar ratio. Binding constants of 2.2 x 10(4), 2.0 x 10(4) and 3.6 x 10(5) dm(3) mol(-1) were calculated for the C3 : Py, C3 : ANS and C3 : NPN complexes (1 : 1), respectively, based on the Benesi-Hildebrand equation.