Charge Transfer Complexes of Lipids with Iodine

Abstract

THERE is much interest in the role of charge transfer interactions in biology¹. In a study of the semiconductive properties of lipids in the solid state, Rosenberg and Jendrasiak (ref. 2 and unpublished work) have shown that when lipid molecules, such as egg lecithin and synthetic lecithin, are exposed to iodine vapour, they exhibit a large increase in electrical conductivity with a concomitant decrease in the activation energy from the dry state value. They suggest that a charge transfer mechanism may be involved. Because they also found that iodine added to the aqueous media surrounding lipid bilayers (egg lecithin or oxidized cholesterol) increased the bilayer conductivity also by a factor of more than 10⁴, it was suggested that a charge transfer mechanism might also be involved in this case. It was with the intention of investigating these possible charge transfer mechanisms that we undertook the work reported here.