Nematic phases driven by hydrogen-bonding in liquid crystalline nonsymmetric dimers

ABSTRACT

A new type of supramolecular liquid crystalline complexes formed by intermolecular hydrogen bond formation between rod-like 4-(4ʹ-pyridylazophenyl)-4ʺ-alkoxybenzoates as proton acceptors and 4-[5-(4ʹ-cyanobiphenyl-4-yloxy)alkyloxy]benzoic acids as proton donors have been designed and prepared. The benzoic acids derivatives consist of two variable aliphatic spacers with odd number of carbon atoms and terminated with the highly polar cyano group. The liquid crystalline behaviour of the new complexes has been characterised using polarised light microscopy (POM) and differential scanning calorimetry (DSC). It was found that regardless the terminal alkyl chain lengths at the pyridine-based component or the length of the flexible spacer on the benzoic acid derivatives; all of the prepared complexes exhibit only enantiotropic nematic phases over a broad temperature range.

KEYWORDS:

• Azopyridine
• hydrogen bonding
• dimers
• nematic phase
• liquid crystals

Disclosure statement

No potential conflict of interest was reported by the authors.