Spectroscopic study of liquid crystalline N-[4-(4-n-alkoxybenzoyloxy)2-hydroxybenzylidene]hydroxyanilines

Abstract

New homologous series of N-[ 4-(4-n-alkoxybenzoyloxy)-2-hydroxybenzylidene ]hydroxyanilines were synthesized. All 4-hydroxyaniline derivatives exhibited a nematic phase, while 3-hydroxyaniline and 2-hydroxyaniline derivatives exhibited only a nematic phase as the terminal alkoxy group was lengthened. Infrared spectra suggest that the 4-hydroxyaniline derivatives form intermolecular hydrogen bonding of the single bridge type, while the 3-hydroxy and 2-hydroxy derivatives form the polymer type. The Raman band at around 1360 cmÕ 1 exhibited large diOE erences in intensity among these derivatives. This can be explained by the eOE ect of intermolecular or hydrogen bonding molecular conformation.