Collect. Czech. Chem. Commun. 1991, 56, 1482-1488

Bis(monoazacrown ether)s: Effects of bridge length and ring size on stability and selectivity in alkali ion sandwich complex formation

Petr Holý, Juraj Koudelka, Martin Bělohradský, Ivan Stibor and Jiří Závada

Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6


Sodium, potassium, rubidium and caesium ion complex formation was investigated in two homologous series of bis(azacrown ether)s Ia-Ic and IIa-IIc. Three complementary bis(azacrown ether)s series IIIa-IIIc, IVa-IVc and Va-Vc were employed for a more detailed study of sodium complexation. Very pronounced effects of bridge length as well as macroring size were found in the investigated series and interpreted mainly in terms of various proclivity of individual ligands and alkali ions to sandwich complex formation. Remarkably high selectivities in alkali ion formation were noted for the shortest bridge ligands Ia and Ib, the former preferring strongly sodium and the latter potassium complex formation.