A comparative study of the properties of the liquid crystalline compounds 5O.5 and 5O.6 in solid, solution and thin film forms by laser Raman spectroscopy

Abstract

Raman spectroscopic studies of the liquid crystalline compounds 5O.5 and 5O.6 revealed that the two aromatic rings in the core are in different environments with distorted electron cloud distributions, and the behaviour of each of these rings is independent of the other. Increased chain length results in the development of strain on the molecules. During the SmF-SmB phase transition there is a slight transfer of charge, along with an increase in the freedom of the individual molecules. Our experiments also reveal that the molecules are strained in the crystalline state and adopt some preferred orientations in free-standing films. There is also a tendency towards the elongation of the molecules along the C=N- linkage in solution for 5O.6. Raman spectra of 5O.6 in free-standing films have shown dramatic changes compared with the spectra recorded in the bulk.