Hydrogen bonding and EDA-interaction in binary systems with liquid crystalline phases

Abstract

An EDA complex, formed by 4,4′diacyldiphenyl (I) and N,N′dialkyl-4,4′diaminodiphenyl (II), which possesses liquid crystalline phases, has been investigated by ir spectroscopy. The EDA interaction is indicated by the yellow colour of the complex. The electronic stack interaction is remarkably enhanced by hydrogen bonds, which act in the plane of the aromatic rings. This has been demonstrated by comparison with a system formed by (I) and the N,N′dimethylated compound II. Although the latter compound is strongly related to II, it lacks proton donor ability. Further D/H isotope exchange has been used to investigate the problem.