IR Absorption and Raman spectroscopic study of reentrant-nematic liquid crystalline N-[4-(4-Octyloxy-benzoyloxy) Benzylidene]-4-Cyanoaniline (OBBC)

Abstract

The IR absorption and Raman scattering of OBBC have been investigated in the solid, ReN, SmA and nematic phases. The intensity of the 2229 cm⁻¹ band assigned to the C[tbnd]N stretching mode decreases with increasing temperature in the reentrant nematic phase; this is attributed to a change in the overlap of the molecules. While the IR bands at 1728 and 841 cm⁻¹ also show a remarkable temperature dependence, Raman bands do not show significant temperature dependence in the liquid-crystal phases.

Key Words:

• Liquid crystals
• Infrared absorption
• Raman scattering
• Phase transition
• Reentrant nematic
• Spectroscopy