Aza crown ether calix[4]arenes containing cation and anion binding sites: effects of metal ions towards anion binding ability

• Published in: Tetrahedron letters Vol. 42; no. 32; pp. 5541 - 5544
• Main Authors: Tuntulani, Thawatchai, Poompradub, Sirilux, Thavornyutikarn, Praput, Jaiboon, Nongnuj, Ruangpornvisuti, Vithaya, Chaichit, Narongsak, Asfari, Zouhair, Vicens, Jacques
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 06.08.2001; Elsevier
• Subjects: anion binding; aza crown; calixarene; Chemistry; Chemistry, Organic; Physical Sciences; proton NMR titration; Science & Technology; anion binding; aza crown; proton NMR titration; calixarene; RECOGNITION; RHENIUM(I) BIPYRIDYL; RECEPTOR; DERIVATIVES
• ISSN: 0040-4039; 1873-3581
• DOI: 10.1016/S0040-4039(01)01029-2

Tripodal aza crown ether calix[4]arenes containing both cation and anion binding sites ( 5a and 5b ) have been synthesized. The X-ray analysis shows that 5a forms a self-threaded rotaxane-like structure in the solid state. 1H NMR titrations of the two ligands with various halide anions indicate that 5a and 5b can form complexes with Br − and I − but not F −. However, both compounds form more stable complexes with I − than with Br − in the presence of Bu 4N +. The presence of K + enhances the binding ability of 5a towards Br −. Compounds 5a and 5b were synthesized and their complexation with halide anions in the presence of various countercations was studied by 1H NMR titrations.