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ABSTRACT
New types of angular 1:1 hydrogen-bonded supramolecular complexes via hydrogen-bond formation between 4-alkoxyphenylazo benzoic acids (In) and 4-(3ʹ-pyridylazo)-4ʹʹ-alkoxybenzoates (IIm) with various alkoxy chains (from 6 to 16 carbons) were prepared and investigated for their mesophase behaviour by differential scanning calorimetry (DSC) and polarised-light microscopy (PLM). All prepared homologues were found to be dimorphic, possessing smectic C and nematic mesophases. The formation of 1:1 hydrogen-bonded supramolecular liquid crystals (LCs) complexes was confirmed by FTIR and UVʹvisible (UVʹvis) absorption spectroscopy. The study revealed that nematic transition enhancement (ΔT) decreases with the increase of the alkoxy chain length on the base complement, while it increases with the increase of the chain attached to the acid complement of the complex, that is the stability of the nematic phase is more dependent on the length of the acid component.
Graphical Abstract
Acknowledgement
The authors show their gratitude to Dr. M. Alaasar (associate professor in organic chemistry, Faculty of Science, Cairo University) for his comments and very helpful discussions that greatly improved the manuscript.
Disclosure statement
No potential conflict of interest was reported by the authors.