Tuning Hydrogen-Bonding with Amide Groups for Stable Columnar Mesophases of Triphenylene Discogens

Abstract

Tuning hydrogen-bonding of discotic liquid crystal can result in more ordered columnar mesophases and higher charge carrier mobility materials. In this paper, triphenylene derivatives with one, two and three amide groups with structure of C₁₈H₆(OR)₅(OCH₂CONHBu), C₁₈H₆(OC₅H₁₁)₄(OCH₂CONHBu)₂ and symmetrical and asymmetrical C₁₈H₆(OR)₃(OCH₂CONHBu)₃ (R = C _n H_2n+1, n = 4–9) respectively were designed and synthesized. The results showed that each intra-columnar H-bond forming amide (–CONH–) group caused an average increase of 22°C in clearing point from the non-H-bonding ester group (–COO–) triphenylene analogous. This was the first quantitative result of H-bonding on the stabilization of columnar mesophase.

Keywords:

• anchorage of columnar phase
• columnar mesophase
• discotic liquid crystal
• intermolecular hydrogen-bonding
• supramolecular liquid crystal
• Triphenylene

Acknowledgments

National Natural Science Foundation of China (project Nos. 50473062 and 50673069) supported this work.

Notes

^a DSC data measured with heating and cooling rate of 10°C/min under N₂ atmosphere. K, crystal. Col, columnar phase. Iso, isotropic liquid.

^a DSC data measured with heating and cooling rate of 10°C/min under N₂ atmosphere. K, crystal. Col, hexagonal columnar phase. Iso, isotropic liquid.

^a DSC data measured with heating and cooling rate of 10°C/min under N₂ atmosphere. K, crystal. Col, columnar phase. Iso, isotropic liquid.

^a DSC data measured with heating and cooling rate of 10°C/min under N₂ atmosphere. K, crystal. Col, columnar phase. Iso, isotropic liquid.

^a DSC data measured with heating and cooling rate of 10°C/min under N₂ atmosphere.

^b monotropic Col phase Col_p, plastic columnar phase. Col, columnar phase. Iso, isotropic liquid.