Synthesis and phase behavior of Y-shaped Schiff base liquid crystal oligomers

ABSTRACT

In this paper, we designed and synthesised three Schiff base mesogenic units X-YP and six Y-shaped liquid crystal oligomers X-AYP and X-BYP (×= -CH₃O, -CH₃, -Cl). Molecular structures of the prepared compounds were confirmed via FT-IR, ¹H NMR and elemental analysis. The mesomorphic properties were investigated by differential scanning calorimetry (DSC) and polarised light microscopy (POM). The photochemical properties of Y-shaped liquid crystal oligomers were preliminarily studied by UV-Vis spectrum. The results indicated that X-YP containing OCH₃ and Cl substituents exhibited mesophase, while X-YP with CH₃ substituent was non-mesogenic. The synthesized Y-shaped liquid crystals X-AYP and X-BYP both had liquid crystal properties and exhibited nematic phase during heating and cooling, which belonged to thermotropic enantiotropic nematic liquid crystals. The polarity of the terminal groups and the number of mesogenic units had a significant effect on the mesophase behaviour of Y-shaped liquid crystals. The absorption intensities of X-AYP and X-BYP in the UV spectra were affected by the terminal substituents.

GRAPHICAL ABSTRACT

KEYWORDS:

• Liquid crystal
• Schiff base
• Y-shaped
• synthesis
• terminal substituent

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was financially supported by the Fundamental Research Fund for the Central Universities [N180705004].