Structures of the Chiral Smectic C Phase with Selective Reflection in the Wavelength Range of Visible Light. I. Interlayer Distances and Helical Pitches of the (+)-4-n-Alkyloxyphenyl 4-(2”-Methylbutyl)-biphenyl 4′-Carboxylates Series

Abstract

Interlayer distances and helical pitches were studied as functions of temperature by X-ray diffraction and transmission spectral measurements for chiral smectic C phases of (+)-4-n-alkyloxyphenyl 4-(2′-methylbutyl)biphenyl 4′-carboxylates, which had selective reflection in the wavelength range of visible light. The relationship between the interlayer distances and the length of the paraffinic chain gives some information about the structure within the layers: the molecular tilt angle (with respect to the normal to the layer plane) is 45–48° and the paraffinic chains form double layers. Interlayer structures and interactions are discussed, in the light of the interlayer distances and the helical pitches.