Synthesis and physical properties of novel S‐shaped liquid crystal oligomers

Abstract

We prepared novel S-shaped liquid crystal oligomers, the 4,49-bis (v-(2-(v-(4-(cyanophenyl)phenyloxy)alkyloxy)phenyloxy)alkyloxybiphenyls (S-n), and investigated their transition behaviour. The oligomer with even-numbered spacers (S-6) exhibited a nematic phase, whereas the oligomer with odd-numbered spacers (S-7) exhibited nematic and smectic A phases. Transition properties of the S-shaped oligomers are compared with those of the corresponding monomeric and U-shaped dimeric compounds. The entropy changes associated with the I-N transition for the oligomers were found to have small values, similar to that of the monomeric compound. A biaxial smectic phase was induced below the SmA phase in some binary mixtures of S-6 and a phenylpyrimidine derivative (8-PYP-6O). On the other hand, the SmA phase was stabilized in the mixtures of S-7 and 8-PYP-6O. We discuss the transition behaivour of the S-shaped oligomers in terms of their molecular shape.

Molecular Organization of Preorganized S-Shaped Oligomers in the Liquid Crystalline Phases

“…Recently, we reported pronounced odd-even effects in the transition behavior of U-shaped systems [12]. Moreover, we have reported the synthesis and transition properties of S-shaped molecules in which two U-shaped mesogenic molecules are connected [13].…”

Playing with Liquid Crystals: A Short Review

“…discotic liquid crystal. 5 However, there are many other categories such as cholesterol-based liquid crystal, H-shaped, 6 S-shaped, 7 star shaped liquid crystal 8 etc. Over a short period of our research on liquid crystal we have synthesized different type of thermotropic liquid crystals and characterized their unique properties with the help of POM, DSC and powdered XRD.…”

λ-Shaped azomesogens with polar chloro- and nitro-substituents

“…Yoshizawa and Yamaguchi [14] have reported layered structure in the nematic phase consisting of U-shaped molecules. Recently Yoshizawa et al [15] have reported the synthesis and physical properties of novel S-shaped LC oligomers in which two U-shaped mesogenic molecules are connected. Yoshizawa et al [16] have also reported novel Y-shaped LC oligomers in which three mesogenic units are connected by 3,5-dihydroxybenzoic acid.…”