Novel triphenylene−ammonium−ammonium−triphenylene-based discotic ionic liquid crystalline dimers

Abstract

In this work, two novel triphenylene−ammonium−ammonium−triphenylene diads were synthesised. The effect of the peripheral chain length around triphenylene and the length of the linker connecting triphenylene with an ammonium moiety on the liquid crystalline behaviour was studied. The molecular structures were verified using proton and carbon nuclear magnetic resonance, mass spectrometry and elemental analysis. The liquid crystalline properties of these compounds were determined by polarising optical microscopy, differential scanning calorimetry and X-ray diffraction studies. These triphenylene−ammonium-based gemini dimers with tetrafluoroborate as the counter ion were found to exhibit liquid crystalline behaviour with a hexagonal columnar phase morphology.

Keywords:

• gemini surfactant
• ionic liquid crystal
• discotic
• triphenylene
• ammonium
• columnar mesophase

Acknowledgements

We thank Mrs Vasudha for technical assistance. We are grateful to Professor V. A. Raghunathan for helpful discussions with the X-ray diffraction results.