Dynamic change of molecular conformation generating a variation of liquid crystalline phases for triphenylene mesogens with peripheral alkoxyazobenzenes

ABSTRACT

A triphenylene mesogen which possesses six dodecyloxyazobenzene units at the periphery linked by propylene-ether chain (2-C12-3) was synthesised and its mesomorphic phase transition behaviour was investigated. It was found that 2-C12-3 exhibits six mesophases including one monotropic phase. The calamitic-discotic bi-mesomorphic phase transition was also observed. As cooling the compound at the temperature of iso phase, SmA phase comes up and further cooling gives Col_ob phase. In comparison to the corresponding ester-linked derivative (1-C12-3), which shows only two mesophases (SmA and Colr), the linkage part connecting triphenylene unit and the peripheral alkoxyazobenzenes significantly affect the molecular ordering in mesophase, though the bi-mesomorphic property is maintained in the case of dedecyloxy chains.

GRAPHICAL ABSTRACT

KEYWORDS:

• Calamitic -discotic bi-mesomorphism
• triphenylene
• azobenzene
• linkage group

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/02678292.2024.2349669.

Additional information

Funding

This study was supported by JSPS KAKENHI Grant Number 19K05630 and 15K05488. The synchrotron radiation experiments were performed using the BL40B2 beamline of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) [proposal no. 2017A1085, 2017B1135, 2018A1207, 2018B1124, 2019A1403, 2019B1077, 2020A1072, 2021B1121, 2021B1122, 2022A1138, and 2022B1191]. Mass spectra measurements were carried out by Mrs. E. Yamagaki and Mrs. Y. Nishikawa in NAIST on “Advanced Research Infrastructure for Materials and Nanotechnology in Japan (ARIM program)” of the Ministry of Education, Culture, Sports, Science and Technology (MEXT).