New series of chalcone derivatives were built up from fluorobenzaldehyde and 4-hydroxyacetophenone as a starting material then further reacted with terminal alkylester chains to obtain the target compounds. The effect of the terminal chain on mesogenic and photochemical properties was discussed in detail. These series consist of four compounds that differ by the length of the alkyl chain.The branched-arm and chiral core quantity affected the liquid crystalline properties. The synthesized compounds were investigated for their liquid crystal properties and mesophase characteristics by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The compounds (5–7) display nematic phase in the heating cycle while there is no liquid crystal behavior of compound (4). Studying the structure–property relationship and the presence of the halogen atom, it was proposed that, the less carbons number in the alkyle chain will increase the phase transition temperature to generate the nematic phase. The molecular structure of the synthesized compounds was confirmed by spectroscopic analysis.

A new six-armed compounds consist of benzene ring as a central core substituted with aromatic ring and three rod-like armed of 2-chloro-4,6-bis(dodecyloxy)-1,3,5-triazine as the peripheral arms unit which obtained by sequential nucleophilic substitution of chlorine atoms in cyanuric chloride. The substitution took place at the acetylenic periphery on the central benzene ring by Sonogashira coupling. Equimolar mixtures of the six-armed compounds based on the benzene core with the complementary 4-dodecyloxybenzoic acid, which already possessed liquid crystal property, resulted in an organic salt. The organic salts and structures were investigated by differential scanning calorimetry (DSC), and confirmed by spectroscopic methods (1H-NMR, 13C-NMR and Mass spectroscopy)