Molecular Engineering of Board-Shaped Mesogens by Synthesis

Abstract
Recently, a board-shaped lead structure to obtain the biaxial nematic phase have been discovered with a promising aspect ratio and a broad nematic phase range. X-ray diffraction exhibited a scattering pattern which appeared to originate only from a rectangular form factor and solid-state NMR (relaxometry) revealed small biaxial clusters to be present in the nematic phase.[1] However, the material did not show any uniform alignment, even not in the electric field and consequently the biaxial phase could not be confirmed by Conoscopy.

This contribution will highlight the versatile synthesis of board shaped mesogens with a library of different peripheral decorations to optimize the aspect ratio, the alignment, the thermal stability and the interaction along the minor director. The nematogens are investigated by polarized optical microscopy, differential scanning calorimetry, X-ray scattering and Conoscopy. Preliminary results confirm the alignment of the nematogens in induced real biaxial nematic phases.

[1] M. Lehmann, S. Maisch, N. Scheuring, J. Carvalho, C. Cruz, P. J. Sebastião, R. Y. Dong, Soft Matter 2019, 15, 8496-8511.