Abstract
New symmetrical 1:2 supramolecular H-bonded liquid crystals (SMHBLCs) interactions, A/2Bn, were formed between adipic acid and 4-(4′–pyridylazophenyl) 4″-alkoxybenzoates. Optical and mesomorphic behaviors of the prepared SMHBLC complexes were investigated using differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (XRD). FT-IR spectroscopy was carried out to confirm the H-bond interactions of the prepared complexes via Fermi bands formation. Their photo-physical properties were investigated by UV-spectroscopy and the observed absorbance values were found to be mainly dependent on the length of the terminal alkoxy chain. Mesomorphic behaviour for all A/2Bn complexes revealed that all complexes are dimorphic-exhibiting enantiotropic mesophases with induced nematic phases, except for the long chain terminal complex which exhibits only a monomorphic smectic A phase. In order to investigate the effect of mesogenic core geometry on the mesophase properties, a comparison was established between the mesomeric behaviors of the present complexes and previously reported rigid core acid complexes. Finally, the XRD pattern confirmed the POM and DSC results.
Highlights
In the last few years, liquid crystal (LC) technologies induced great effects in different engineering display applications [1,2,3,4]
The H-bonding interactions were confirmed via Fermi-bands observations in FT-IR spectroscopic analysis
The mesomorphic behaviors of present supramolecular hydrogen-bonded liquid crystals (SMHBLCs) complexes were investigated by Differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (XRD)
Summary
In the last few years, liquid crystal (LC) technologies induced great effects in different engineering display applications [1,2,3,4]. The formation of photosensitive supramolecular hydrogen-bonded liquid crystals (SMHBLCs) through intermolecular hydrogen bonding (H-bonding) interactions occupies a wide area of interests [11,12,13,14,15,16,17,18,19]. The molecular architecture and the length of the terminal flexible chain of the liquid crystalline molecule play a significant role in the formation, type, thermal stability and temperature range of the mesophase. In such cases, as the terminal chain length increases, the molecules will be oriented in a parallel arrangement [26]. The terminal chain length has an important role in influencing
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