Synthesis and mesomorphic behavior of symmetrical chiral liquid crystal dimers incorporating ester linked biphenyl- naphthyl cores and terminal vinyl group

ABSTRACT

A series of symmetrical chiral, liquid crystal dimeric molecules possessing ester- linked, biphenyl-naphthyl cores with varied spacer lengths and terminal vinyl groups have been synthesized using Naproxen as the synthetic precursor. The synthesized symmetrical chiral dimers were characterized by 1H NMR spectroscopy, and their liquid crystalline behavior was confirmed by DSC and HOPM studies. Structural effects on the mesomorphic and physicochemical properties were investigated in terms of variation of chiral chain length. The synthesized dimeric compounds exhibited SmX^*, SmC^*, SmA^*, N^*, BPI^*, and BPII^* mesophase sequences. An odd-even effect was observed in the dimers and the duration of the mesophase decreased with increasing spacer length. The synthesized vinyl substituted liquid crystalline dimers are particularly useful in understanding liquid crystal polymorphism and act as model compounds for liquid crystal polymers.

KEYWORDS:

• Chiral dimers
• liquid crystal
• odd-even effect

Acknowledgements

The authors express their sincere appreciation and gratitude to the Department of Chemistry, Anna University, Chennai, and Oklahoma Baptist University for financial support. The authors also thank Dr. K.D. Berlin for his valuable guidance towards this research work.