Synthesis of new calixarene ligands

Ionic recognition is major field of application for supramolecular chemistry. This has led to the development of extractants that selectively exfract desired cations from an aqueous phase, chemosensors (e.g., chromoionphores and fluoroionophores), ionselective elecfrodes for detecting certain cations selectively and directiy in aqueous phases, stationary phases of chromatographic columns for ion separations and membranes for fransporting a desired cation selectively.

Recent studies of the Bartsch Research Group on calix[4]arenes have focused on preparation of conformationally mobile or restricted calix[4]renes and calixbiscrown ethers for metal ion separations.'^^'''^ N-(X)sulfonyl groups were attached to the calix[4] arene to give proton-ionizable calix[4]arenes with tunable acidity.

The object of the thesis research is the synthesis of di-ionizable calix[4]arenecrown compounds. By infroducing two proton-ionizable groups into calix[4]arene-crown-6 compounds, the ligands will be conformational fixed. The possibility of synthesizing different conformational isomers will be probed. By attaching the two proton-ionizable groups to different positions, 1,2- and 1,3- disubstituted calixcrowns can be prepared. While the basic platform is retained, dansyl (5-dimethylamino-l-aaphthalene-sulfonyl) fluorescent groups (Figure 1.8) will be attached to provide potential fluoroionophores.