Biphenylyl-1,2,4-oxadiazole based liquid crystals – synthesis, mesomorphism, effect of lateral monofluorination

ABSTRACT

Aiming at developing a new type of materials for functional applications, three series of new compounds were prepared, 3-(biphenylyl)-1,2,4-oxadiazoles, Series I; laterally mono-fluorinated 3-(biphenylyl)-1,2,4-oxadiazoles, Series II; and 5-(biphenylyl)-1,2,4-oxadiazoles, Series III. Liquid crystalline properties of these compounds were studied using differential scanning calorimetry and polarizing optical microscopy. Ten of the thirteen compounds in Series I are mesogenic forming either N or SmA phases depending on the length-to-width molecular ratio. Mesogens of the positional isomers, Series III are both N and SmA. Monofluorination of the biphenylyl group at either the central or the terminal phenylene rings, Series III, resulted in the formation of nematic mesogens with low phase transition temperatures and broad nematic phase range.

Graphical Abstract

KEYWORDS:

• Heteroaromaic liquid crystals
• wide nematic
• low temperature nematic
• 1,2,4-oxadiaxoles
• biphenyl
• fluorinated liquid crystals

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

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Additional information

Funding

This work was supported by the 2013–2015 National Science Foundation, Research Experiences for Undergraduates [REU-NSF 1263087];NSF [1435195].