Triphenylene discotic liquid crystal trimers synthesized by Co 2(CO)8-catalyzed terminal alkyne [2 + 2 + 2] cycloaddition

Han, Bin; Hu, Ping; Wang, Bi Qin; Redshaw, Carl; Zhao, Ke Qing

Abstract

The synthesis of star-shaped discotic liquid crystal trimers using Co 2(CO)8-catalyzed terminal alkyne [2 + 2 + 2] cycloaddition reaction is reported. The trimers consist of three triphenylene discotic units linked to a central 1,2,4-trisubstituted benzene ring via flexible spacers. The trimers were synthesized in the yields up to 70% by mixing the monomers with 10 mol % of Co2(CO)8 as the catalyst in refluxing 1,4-dioxane. The liquid crystalline properties were investigated by using polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Trimer 4 with an ester connecting group and a longer spacer exhibited a rectangular columnar mesophase, while 5b and 5c possessing an ether linkage and a shorter spacer display a hexagonal columnar mesophase. The connecting functional group and the length of the flexible spacer between the central benzene ring and the triphenylene units have pivotal influence on the mesomorphism. © 2013 Han et al; licensee Beilstein-Institut.

Citation

Han, B., Hu, P., Wang, B. Q., Redshaw, C., & Zhao, K. Q. (2013). Triphenylene discotic liquid crystal trimers synthesized by Co 2(CO)8-catalyzed terminal alkyne [2 + 2 + 2] cycloaddition. Beilstein Journal of Organic Chemistry, 9, 2852-2861. https://doi.org/10.3762/bjoc.9.321

• Journal Article Type: Article
• Acceptance Date: Nov 14, 2013
• Publication Date: Dec 11, 2013
• Deposit Date: Jun 8, 2022
• Publicly Available Date: Dec 12, 2022
• Journal: Beilstein Journal of Organic Chemistry
• Print ISSN: 1860-5397
• Publisher: Beilstein-Institut
• Peer Reviewed: Peer Reviewed
• Volume: 9
• Pages: 2852-2861
• DOI: https://doi.org/10.3762/bjoc.9.321
• Keywords: Co2(CO)8 catalyzed cycloaddition; Columnar mesophase; Discotic liquid crystal; Triphenylene; Oligomer
• Public URL: https://hull-repository.worktribe.com/output/3621925