X-ray Characterization of Two Cubic Phases and a Structured Liquid Phase of 4′-n-Alkoxy-3′-nitrobiphenyl-4-carboxylic Acids (ANBC-n)

Abstract

The cubic D (CubD) and structured liquid (I₁) phases of 4′-n-alkoxy-3′-nitrobiphenyl-4-carboxylic acids (ANBC-n, where n is the number of carbons in the alkoxy group) have been investigated by X-ray diffraction techniques. The type of the CubD phase was identified as Ia3d for the homologues with n=15, 19, 20, 22, and 26, similarly to those of n=16 and 18. On the basis of the model proposed by Luzzati and Spegt, the diameter (D/Å) and the length (L/Å) of the constituent rod are estimated and discussed. The structure of the I₁ phase and its dependence on n are also discussed. For n=26, very surprisingly, another cubic phase with Im3m symmetry was observed at the lower temperature side of the Ia3d cubic phase on heating.

Key Words:

• cubic phase
• structured liquid
• 4′-n-alkoxy-3′-nitrobiphenyl-4-carboxylic acids