Columnar mesomorphism from a new luminescent thiazolo[5,4-d]thiazole-based core

ABSTRACT

Two new mesogenic compounds having a bicyclic aromatic thiazolo[5,4-d]thiazole linked to four 1,3,4-oxadiazol heterocycles were synthesised and their liquid-crystalline properties were investigated. The compounds exhibit enantiotropic hexagonal columnar mesophase with strong homeotropic orientation induced under confinement, and a wide mesophase range. The molecular packing is preserved at room temperature, especially the π-stacking inside the columns, which is essential for good charge carrier transport. They show high thermal stability, blue photoluminescence in solution, and blue-green in thin film. The morphology of spin-coated films is smooth even after thermal annealing, where large molecular-ordered domains were induced, but preserving the photoluminescence quantum yield. All characteristics suggest that this new class of mesogenic molecules is promising for technological applications.

Graphical abstract

KEYWORDS:

• Columnar mesophase
• thiazolo[5,4-d]thiazole
• thermal properties
• X-ray diffraction
• photoluminescence

Acknowledgments

The authors thank to CNPq, CAPES/PROCAD, FAPESC, FACEPE, INCT/INEO, INCT-Catálise and INCT-INAMI for financial support. The XRD experiments were carried out in the Laboratório de Difração de Raios X (LDRX/UFSC). CEBIME carried out the mass spectrometry analysis.

Disclosure statement

The authors declare no conflict of interest.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico [303763/2018-3,431505/2016-0,444061/2018-5].