BEHAVIOR OF METACROWNOPHANES AT ALKALI-ME TAL CATION-TRANSPORT

Metacrownophanes (2) (with two methoxyl groups on the aromatic nuclei) and (3) were conveniently prepared by means of intramolecular [2+2] p hotocycloaddition of styrene derivatives in acetonitrile. It was sugge sted from the examination of H-1-NMR spectra that the syn-conformation of the simple metacrownophane (3) became predominant in the presence of alkali metal salts in contrast to (2) that had anti-conformation (T able 1). When they were used as carriers for alkali metal cations with dodecanoic acid in chloroform membrane systems, crownophane (3) showe d higher efficiency (especially toward Li+ ion) than that of (2) (Tabl e 2), indicating its smooth conformational change between syn- and ant i-form.