Self-assembled star-shaped liquid crystals based on 1,3,5-trihydroxybenzene with pendant alkyloxylated azobenzene arms

ABSTRACT

Designing and self-assembly of unconventional star-shaped mesogens or ‘hekates’ are of interest to materials science and molecular electronics. This work presents the synthesis of several symmetric trimeric liquid crystalline compounds comprising 1,3,5-trihydroxybenzene (phloroglucinol) as central core. The liquid crystalline behaviour was induced by attaching three rod-like azo-aromatic semi-flexible units to the central core via esteric linkages. Based on differential scanning calorimetry and polarising optical microscopy, the mesophase stability mainly depends on the alkyl chain length. The compounds showed monotropic or enantiotropic behaviour, except the compound with nine atoms on the chain end which is non-mesomorphic. In addition to the synthesis and mesophase characterisation, the self-assembled structures and individual properties have been characterised by molecular simulations.

Graphical Abstract

KEYWORDS:

• Star-shaped liquid crystals
• hekates
• phloroglucinol
• azobenzene
• discotic

Acknowledgments

E.L. Epure would like to thank the Gheorghe Asachi Technical University of Iasi for funding by a National Research Grants of the TUIASI, project number GnaC2018_91/2019.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the National Research Grants of the TUIASI [project number GnaC2018_91/2019].