Synthesis and liquid crystalline properties of new chalcone derivatives central linkages

Abstract

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.

Keywords:

• Alkylester
• chalcone
• mesomorphic
• nematic liquid crystalline
• synthesis and characterization