The synthesis of new 25,27-dialkyloxy-5,17-diarylcalix[4]arenes-crown-6 1a -f in 1,3-alternate conformation by Suzuki cross-coupling reaction is reported. Their conformation was determined using 1 H, 13 C, 2D NMR and ROESY analysis, and X-ray crystallography. Extraction experiments using a two-phase solvent method involving sodium, potassium or cesium picrate showed good extraction of the cesium cation. The X-ray crystal structures of 1,3-alternate 25,27-dipropoxy-5,17-diphenylcalix[4]arene-crown-6 ether 1a and its cesium picrate complex were established. Solid-state data were used to determine the complexation behavior of these new ligands. The efficiency of calixarenes 1a -f for cesium ion extraction could be ascribed to the rigidity and flatness linkages caused by the aryl groups at the lower rim of the aromatic moieties in the calixarene skeleton. In addition, the introduction of these aromatic moieties in positions 5 and 17 enhanced the solubility of the metal complexes in organic media.
Due to their interesting selective binding abilities towards alkali cations, calixcrowns constitue an important class of macrocyclic compounds combining calixarene and crown ether frameworks. Particularly important are the dialkoxycalix[4]arene-crown-6 derivatives and analogous bis-(crown-6) in the 1,3-alternate
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