New mesogenic compounds possessing a biphenyl ester and ether moiety comprising 1,3-dimethylbarbituric acid: synthesis, characterisation and mesomorphic studies

ABSTRACT

New substituted derivatives of 5-vinyl-1,3-dimethylbarbituric acid were synthesised and evaluated for liquid crystal properties. Two sets of molecules were prepared. One end of all the molecules possesses the 1,3-dimethylbarbituric core. The first set comprises biphenyl ethers, 4a–n and the second set biphenyl esters, 5a–g. Liquid crystalline properties were investigated by POM and DSC techniques. All the compounds exhibited enantiotropic smectic A and nematic mesophases. The LC properties were found to depend on the spacer and terminal alkoxy- chain and alkoxy- ester moiety of the molecules. Smaller alkyl chain members showed a smectic phase, while higher alkyl chain members showed a nematic phase.

GRAPHICAL ABSTRACT

KEYWORDS:

• Liquid crystals
• dimethyl barbiturates
• dimers
• mesophases
• heterocycles

Acknowledgements

AK-T M extends grateful thanks to Prof. John West and Liquid Crystal Institute at Kent State University for performing theoretical calculations, and their hospitality.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Additional information

Funding

The authors would like to thank the University of Anbar, Iraq and Universiti Sains Malaysia for supporting this project.