Preparation of conjugated polymeric columns with a hexagonal symmetry from star-shaped supramolecular liquid crystals

Abstract

New conjugated polymeric columns with a hexagonal symmetry were prepared via topochemical polymerisation of star-shaped supramolecular liquid crystals formed by hydrogen bonding between a phloroglucinol core and pyridine derivatives containing a diacetylenic group in the alkyl chain. The mesomorphic properties of the supramolecular monomer and its photopolymerisation behaviour were investigated. The supramolecular liquid crystal exhibited a rectangular columnar mesophase. Photopolymerisation of supramolecular monomer along the column axis in the liquid crystalline state provided well-ordered conjugated polydiacetylenic columns with a two-dimensional hexagonal symmetry. Fourier transform infrared and ultraviolet–visible spectroscopy affirmed that conjugated polydiacetylenes were produced by 1,4-polymerisation of the supramolecular monomer along the column axis. X-ray diffraction analysis showed that a two-dimensional columnar order in the supramolecular monomer was maintained after photopolymerisation, and that the resulting polydiacetylene had a hexagonal array of conjugated columns. Our controlled methodology provides a new route to conjugated polymeric columns with highly ordered structures by self-assembly and polymerisation of star-shaped supramolecular liquid crystals.