Star-shaped supramolecular liquid crystals formed by hydrogen bonding between phloroglucinol and stilbazole derivatives with different molecular shapes

Abstract

Three types of the stilbazole derivative, 4-(4-alkoxybenzoyloxy)-4′-stilbazole (nSz), 4-(3,4-dialkoxybenzoyloxy)-4′-stilbazole (nDSz), and 4-(3,4,5-trialkoxybenzoyloxy)-4′-stilbazole (nTSz), were synthesised and complexed via hydrogen bonding with phloroglucinol (PG) to build liquid crystals, and their mesomorphic properties were investigated. In PG/nSz complexes, a wider mesomorphic range was observed than in nSz. The types of observed mesophases were nematic (n = 6, 8) and smectic phases (n = 10, 12). PG/nDSz and PG/nTSz complexes showed mesophases which were not observed for the non-complexed components. Monotropic nematic phases were observed for the PG/nDSz complexes, and PG/nTSz complexes exhibited hexagonal columnar structures. Based on the X-ray diffraction data, schematic models for the molecular arrangement were proposed for the smectic, nematic and hexagonal columnar phases of the complexes.

Keywords:

• hydrogen bonding
• liquid crystal
• self-assembly
• stilbazole
• supramolecule

Acknowledgements

This research was supported by the Public Welfare & Safety Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2010-0020455).