Copper-free click chemistry between azides and internal alkynes for triphenylene discotic liquid crystal trimer formation

Abstract

Click chemistry continues to attract much attention and is widely used in a variety of synthetic areas. However, it is a challenge to do this type of reaction in the absence of a copper catalyst. In this report, we overcome this problem and synthesise two non-C 3 symmetric triphenylene discotic liquid crystal trimers by a copper-free click reaction involving a linear internal alkyne and an azide. Both products are liquid crystals at room temperature; one trimer exhibits an ordered hexagonal columnar mesophase (Colho) and a plastic hexagonal columnar mesophase (Colhp) on cooling, and just a plastic hexagonal columnar on heating, whilst the other displays an ordered rectangular columnar mesophase (Colro).