Title

Thiophene Substituted 1,3,5-Triazines as Building Blocks for Liquid Crystals

Date of Award

10-3-2022

Publication Type

Thesis

Degree Name

M.A.Sc.

Department

Chemistry and Biochemistry

Supervisor

S. Eichhorn

Keywords

Liquid crystals, 1, 3, 5-triazines, Thiophene substituted

Rights

info:eu-repo/semantics/openAccess

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Abstract

Discotic liquid crystals (DLCs), due to their self-organizing and self-healing properties, have been used in organic electronic devices. Generally, DLCs consist of a rigid central aromatic core that is substituted with peripheral flexible chains. Nanosegregation between their conjugated cores and the flexible sidechains often generates π-π columnar stacks that show a high charge carrier mobility. This thesis explores trithiothiphene-1,3,5-triazine based molecules with conjugated but conformationally flexible cores as building blocks for DLCs. Previous work has shown that these C3-symmetric (star-shaped) compounds with alkyl chains directly attached to the three thiophenes are not mesomorph. Studied here are derivatives with thioethers as linking groups that have shown to support self-organization. The compounds were obtained by Stille coupling of thiophene and bithiophene derivatives with cyanuric chloride in good yields. Unfortunately, analysis by differential scanning calorimetry (DSC) and polarized optical microscopy (POM) confirmed the absence of any mesomorphism. The 2-alkylthiothiophene and 5-alkylthio-2,2'- bithiophene precursors were successfully used for the preparation of potentially mesomorphic diacetylene derivatives and two SmA liquid crystals when attached to 2-phenylbenzoxazole. Finally, cyanuric chloride was reacted with chlorinated and fluorinated benzene boronic acids to explore the potential for a stepwise Suzuki coupling with cyanuric chloride. Unexpectedly, the fluorinated boronic acids did not couple and the chlorinated boronic acids reacted with low yields <25% whereas benzene boronic acid reacted in good yields under the same conditions.

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