Synthesis and Properties of Isothiocyanato Pyrimidine Acetylene Liquid Crystals

The pyrimidine ring outside of the rigid core ring of liquid crystal molecules used as a polar mesogenic group, can effectively increase the molecular dipole moment and intermolecular force, improve the dielectric anis-otropy of the compounds, reduce the driving voltage of the liquid crystal, and also favor to form some smec-tic phases. In this paper, where pyrimidine acetyleneisused as the central structural unit and isothiocyanide asthe end group, we could see that a series of liquid crystal compounds (nBTM-NCS) about five compounds were designed and synthesized. The molecular structure of all compounds were identified by IR, H-1-NMR, C-13-NMR and MS spectra, and their liquid crystal properties were measured by differential thermal analyzer (DSC) and polarizing microscope (POM).The experimental results show that all the compounds have the correct molecular structure and smectic phases. The melting point of the compounds is high and it shows a parity effect. Its optical anisotropy reaches about 0.45, and the dielectric constant is about 22 to 24. It can be used as the components for ferroelectric liquid crystals and polymer-dispersed liquid crystal materials.