Different disk structures in the hexagonal columnar mesophases of 2,3‐dicyano‐6,7,10,11‐tetraalkoxy‐1,4‐diazatriphenylenes and 2,3‐dicyano‐6,7,10,11‐tetraalkoxytriphenylenes

Abstract

We have synthesized two series of C_2v symmetric discotic liquid crystals of 2,3‐dicyano‐6,7,10,11‐tetraalkoxy‐1,4‐diazatriphenylene [referred to as (C _n O)₄DADCT (1); n = 8, 10, 12, 14] and 2,3‐dicyano‐6,7,10,11‐tetraalkoxytriphenylene [referred to as (C _n O)₄DCT (2); n = 8, 10, 12, 14]. Polarizing microscopic observations, differential scanning calorimetry and temperature‐dependent X‐ray diffraction studies revealed that each of the (C _n O)₄DADCT (1) and (C _n O)₄DCT (2) derivatives exhibits a hexagonal ordered columnar (Col_ho) mesophase, and that each of the (C _n O)₄DADCT (1) derivatives forms monomer disks in the Col_ho mesophase, whereas each of the (C _n O)₄DCT (2) derivatives forms dimer disks in the Col_ho mesophase. It is very interesting that the different disk structures may originate from the kind of atoms at the α‐position to the CN groups in (C _n O)₄DADCT (1) and (C _n O)₄DCT (2).

Acknowledgements

This work was partially supported by a Grant‐in‐Aid for the 21st Century COE Program and a Grant‐in‐Aid for Science Research (18039013) in a Priority Area “Super‐Hierarchical Structures” from the Japanese Ministry of Education, Culture, Sports, Science and Technology.