NEW PODANDS AND MACROCYCLES CONTAINING DIOXAZAPHOSPHOCANE MOIETIES - SYNTHESIS, STRUCTURAL DETERMINATION AND STUDY OF THEIR BINDING AND IONOPHORIC PROPERTIES WITH CA2+ AND MG2+ CATIONS

The reactions of diacids with the bicyclophosphane 1 lead to podands 3 a-f in which two dioxazaphosphocane moieties are linked by a more or l ess rigid spacer owing to the starting diacid. Macrocycles 4a-b are ob tained by cyclization of podands 3a-b by way of Michaelis-Becker react ion. The formation of Ca2+ and Mg2+ complexes with 3a-f and 4a-b has b een investigated by UV, LR and NMR spectroscopies. Liquid-liquid extra ction studies show for macrocycles efficient extracting properties and good selectivities of Ca2+ towards Mg2+. The calcium transport across a chloroformic membrane agrees better with stability constants than w ith extraction data. (C) 1998 Elsevier Science Ltd. All rights reserve d.