2-(4-Biphenylyl)-1,3,4-oxadiazoles: synthesis and mesogenic studies

ABSTRACT

A series of 2-(4-biphenylyl)-1,3,4-oxadiazoles bearing alkyl or alkoxy substituents at the 4ʹ position, and a hydrogen, or alkyl substituent (linear, branched, fluorinated or functionalised) at the 5 position were synthesised and characterised (51 compounds). Their mesogenic properties were evaluated using differential scanning calorimetry and polarising optical microscopy. Results show that substitution of the 1,3,4-oxadiazole ring for a terminal benzene ring in a conventional p-terphenyl enriched the mesogenic properties. Most of the new oxadiazole compounds exhibit either monotropic or enantiotropic smectic A mesophases with widths ranging from 3 to 50°C. A few compounds (short tailed) exhibit nematic phases and some compounds with branched or fluorinated alkyl substituents at the 5 position are also mesogenic.

Graphical Abstract

KEYWORDS:

• 1, 3, 4-oxadiazole
• biphenyl
• smectic A
• nematic
• heterocycle

Disclosure statement

No potential conflict of interest was reported by the authors.

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