Laterally substituted biphenyl benzoates ‒ synthesis and mesomorphic properties

ABSTRACT

We have synthesised several series of dialkoxy-terminated biphenyl benzoates with lateral substituents (X = F, Cl) in the vicinity of the ester linking group, varying the length of the terminal alkyl chains. The aim was to study mesomorphic properties of these new compounds and compare them with the previously reported analogous phenyl biphenylcarboxylates, which possess reverse orientation of the ester linking group. The studied compounds were characterised by differential scanning calorimetry, polarising optical microscopy and birefringence measurements. For selected homologues, the type of mesophases was confirmed by x-ray scattering analysis. We calculated the dipole moments and suggested its correlation with the preference of tilted smectic phases in studied biphenyl benzoates. Generally, lateral substitution causes the drop of phase transition temperatures as well as melting points, giving rise to mesophases in a wide temperature range, in several cases down to the room temperature.

Graphical Abstract

KEYWORDS:

• Biphenyl benzoates
• lateral substitution
• nematics
• smectic phases

Acknowledgments

The project was financially supported by the Czech Science Foundation (project No. 18-14497S) and Operational Programme Research, Development and Education financed by European Structural and Investment Funds and the Czech Ministry of Education, Youth and Sports [project No. SOLID21 - CZ.02.1.01/0.0/0.0/16_019/0000760]. N.P. thanks Damian Pociecha and Ewa Gorecka for kind hospitality and help with XRD measurements during her stay at Warsaw University.

Disclosure statement

The authors declare no conflict of interests.

Supplementary material

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Additional information

Funding

This work was supported by the Grantová Agentura České Republiky [18-14497S].