NMR and Raman Scattering Studies of MBBA and EBBA

Abstract

The refined broad line NMR spectra of MBBA and EBBA and the Raman spectra in the low frequency region (100 ∼ 650 cm⁻¹) of EBBA are given. The band associated with the accordion mode vibration of the end butyl chain of these molecules is assigned to 280 cm⁻¹ in Raman spectrum. The analysis of accordion mode vibration indicate that the end butyl chain EBBA molecule tends to take all trans conformation, and that that of MBBA molecule tends to take the conformation which has constraint, such as gauche conformation. Assuming that the whole molecular conformation of each sample in the nematic phase, assignments between protons attached to each molecule and each line in the NMR spectrum are given. Molecular and segmental motions, molecular packing, and orientational order in the nematic phase of these samples are discussed.