The Mesomorphic Properties of Chalcone Dimer Derivatives

Abstract

A homologous series of symmetrical dimers viz bis (4-n-alkoxy benzoyloxy) α-phenyl β-benzoyl-ethylenes was synthesized and studied with a view to understanding the relation between molecular structure and the mesomorphic behavior. Twelve members of the dimeric series were synthesized, and the methoxy to butyloxy homologues are not liquid crystals, but the pentyloxy to hexadecyloxy are liquid crystals. The pentyl to heptyl dimers are only nematogenic, but the higher homologues show smectogenic mesomorphism prior to nematogenic mesophase formation. The phase diagram of phase transition curves behaves in a normal manner except for the smectic to nematic transition curve which behaves in an unexpected manner. The smectic and nematic thermal stabilities are 103°C and 131.7°C, respectively. The smectogenic and nematogenic phase lengths vary between 17.4°C to 28.3°C and 2.1°C to 29.9°C, respectively. The liquid crystal properties of presently investigated novel chalcone dimers are compared with known monomeric chalcones.

Keywords:

• Liquid crystal
• mesogen
• mesophase
• nematic
• smectic

Acknowledgments

The authors thank the Department of Chemistry (DST-FIST Funded & UGC-SAP Sponsored) Saurashtra University, Rajkot, for research work. Authors are also thankful to Dr. A.V. Doshi, Ex. Principal M.V.M. Science and Home Science College Rajkot, for his valuable cooperation during present investigation as and when needed. Also thanks are due to the National Facility for Drug Discovery through New Chemical Entities (NCE's), for analysis of samples.