Novel biphenyl-substituted 1,2,4-oxadiazole ferroelectric liquid crystals: synthesis and characterization

Mahabaleshwara Subrao; Dakshina Murthy Potukuchi; Girish Sharada Ramachandra; Poornima Bhagavath; Sangeetha G Bhat; Srinivasulu Maddasani

doi:10.3762/bjoc.11.26

Novel biphenyl-substituted 1,2,4-oxadiazole ferroelectric liquid crystals: synthesis and characterization

Beilstein J Org Chem. 2015 Feb 11:11:233-41. doi: 10.3762/bjoc.11.26. eCollection 2015.

Authors

Mahabaleshwara Subrao¹, Dakshina Murthy Potukuchi², Girish Sharada Ramachandra³, Poornima Bhagavath³, Sangeetha G Bhat³, Srinivasulu Maddasani³

Affiliations

¹ Department of Chemistry, Manipal Institute of Technology, Manipal University, Manipal - 576 104, India ; Syngene International Ltd., Biocon Park, Bommasandra, Bangalore - 560 099, India.
² Department of Physics, University College of Engineering, Jawaharlal Nehru Technological University: Kakinada, Kakinada - 533 003, India.
³ Department of Chemistry, Manipal Institute of Technology, Manipal University, Manipal - 576 104, India.

Abstract

Two novel series of unsymmetrically substituted 1,2,4-oxadiazole viz., R.Ox.C(*)C n compounds are synthesized and characterized. An optically active, (S)-(+)-methyl 3-hydroxy-2-methylpropionate is used to introduce a chiral center in the molecule. A biphenyl moiety prepared by Suzuki coupling reaction is directly attached to the oxadiazole core at C-5 position. Investigations for the phase behavior revealed that the series with a benzyl group on one end of the oxadiazole core exhibits an 1D orthogonal smectic-A phase while the second series with dodecyl flexible end chain shows orthogonal smectic-A and tilted chiral smectic-C (SmC*) phases over a wide range of temperatures. The smectic-C phase exhibits ferroelectric (FE) polarization switching. The mesomorphic thermal stabilities of these compounds are discussed in the domain of the symmetry and the flexibility of the alkyloxy end chain length attached to the chiral center.

Keywords: 3,5-disubstituted-1,2,4-oxadiazoles; SmC* phase; Suzuki coupling; ferroelectric switching; mesomorphism; optical textures; spontaneous polarization.