Chiral and orientationally ordered fluid mesophases formed by oxadiazole bisaniline based achiral bent mesogens

ABSTRACT

Development of new liquid crystalline materials exhibiting interesting properties and phases continues to be an enabling enterprise in the forward march of their successful display and non-display applications. The design and synthesis of a homologous series of liquid crystalline bent-core compounds derived from the oxadiazole bisaniline moiety and the phase behavior of three members of the series that exhibit nematic, smectic C, and dark conglomerate phases is reported. The liquid crystalline phases exhibited by these mesogens are characterized using polarized optical microscopy, differential scanning calorimetry and x-ray scattering techniques. All three homologs prepared exhibit the nematic phase. Interestingly, the homolog with short hexyl terminal chains exhibits only the nematic phase that is stable over a very broad, nearly 100 K wide, temperature range. The compound with terminal octyl chains shows the chiral dark conglomerate phase below the nematic phase despite the bent molecules being achiral. The homolog with dodecyl alkyl chains is found to possess the smectic-C and two additional lamellar phases besides the nematic phase. These compounds enrich the library of achiral bent-core materials capable of exhibiting chiral and nematic phases.

Graphical Abstract

KEYWORDS:

• Bent-core liquid crystals
• oxadiazole bisaniline
• dark conglomerate phase
• chirality
• nematic phase

Acknowledgements

The authors thank Dr. Tawfik A. Khattab and Prof. R. Twieg, Department of Chemistry and Biochemistry, Kent State University for DSC measurements.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplementary data for this article can be accessed here.

Additional information

Funding

This work was supported by the National Science Foundation under the US Ireland R&D Partnership Program Award # DMR-1410649.