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- ISSN: 1570-1786
- E-ISSN: 1875-6255
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Synthesis and Phase Transition Behaviors of Laterally Disubstituted Liquid Crystals Containing 2,5-Dimethyl-1,4-phenylenediamines
- Source: Letters in Organic Chemistry, Volume 22, Issue 11, Nov 2025, p. 883 - 896
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- 13 Dec 2024
- 24 Feb 2025
- 01 Nov 2025
Abstract
A new series of low molar mass mesogens having double lateral substituents were prepared and characterized with the objective to explore the effect of structure modification on the mesomorphic behavior. The molecular structure has three aromatic rings at the centre core system, which is connected by an imine linking group, two flexible alkyloxy chains at both sides of molecules and two lateral methyl groups attached to the core system. This low molar mass mesogen is known as bis(4-alkyloxybenzylidene)-2,5-dimethyl-1,4-phenylenediamine with different numbers of carbon (n) at the alkyloxy chain. Molecular structures were confirmed via infrared and nuclear magnetic resonance spectroscopic and mass spectrometric methods. Phase transition studies were conducted using a differential scanning calorimeter. Whereas, mesophase characterization was determined by polarizing optical microscopy and the temperature was varied with a temperature controller. The current core system of benzylidene-1,4-phenylenediamine showed good potential of exhibiting liquid crystal as all compounds were found to exhibit a nematic phase. Double lateral methyl atoms at the central mesogenic core had broadened the molecular width. This has caused a reduction in the overall lateral intermolecular attraction, and therefore, it exhibited a nematic phase. As the number of carbons at the alkyloxy chain increased, the clearing temperatures were observed to show a descending trend. A comparison of thermal properties was made between the current compounds with analogous compounds that do not possess any lateral substituent or have a single lateral substituent attached to the mesogenic core.
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