4-Octylphenylazo-4′-phenyl alkanoates – homologous series of azomesogens with extremely rich liquid-crystalline polymorphism

ABSTRACT

This paper presents synthesis and liquid-crystalline properties of full homologues series (from acetate to arachidate) of 4-octylphenylazo-4′-phenyl alkanoates. All of the 19 synthesised compounds are liquid crystals with extremely rich mesomorphism. The ester chain length strongly influences mesogenic behaviour of presented materials. In some compounds, up to four liquid-crystalline phases have been observed. There were six different mesophases detected: nematic, smectic C, smectic F, smectic I, J and G. Moreover, some homologues display two crystalline forms. This latter phenomenon does not depend on the ester chain length. Identification of such complicated phase sequences was made based on four methods: polarised light microscopy, thermo-optical analysis, differential scanning calorimetry and X-ray measurements.

Graphical Abstract

KEYWORDS:

• Liquid crystals
• azobenzene
• smectic
• DSC
• XRD

Acknowledgement

Authors thank Dr. Urszula Jarek-Mikulska for fruitful discussion and valuable comments.

Disclosure statement

No potential conflict of interest was reported by the authors.

supplemental data

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