Evolution Structurale d'un Derive Mesogene: le di[(n-butyl)-4 phenyl]-2,6 TTF

Abstract

The structural evolution from the crystal to the mesophase has been studied for the di[(n-butyl)-4 phenyl,]2,6 TTF, taken as an example. The phase sequence is as follow:

The C₂ phase crystal structure has been solved. Analysis of the other phases have been performed by a thorough investigation of Guinier-Lenné diagrams. It particuarly allows to propose a structural arrangement for the crystalline C₁ phase. All phases, excepted N and I ones, show sheet arrangement. The transition from any phase to the following one takes place by a glide of molecules with regard to others, corresponding to a progressive decrease of tilt angle, which goes from ∼ 70° for C₂ to ∼ 50° for C₁ then ∼ 30° for So and finally ∼ 10° for S′_G.