Synthesis and DFT Investigation of New Low-Melting Supramolecular Schiff Base Ionic Liquid Crystals

Autor: Sayed Z. Mohammady, Daifallah M. Aldhayan, Mohsen M. T. El-Tahawy, Mohammed T. Alazmid, Yeldez El Kilany, Mohamed A. Zakaria, Khulood A. Abu Al-Ola, Mohamed Hagar
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Crystals, Vol 12, Iss 2, p 136 (2022)
Druh dokumentu: article
ISSN: 2073-4352
DOI: 10.3390/cryst12020136
Popis: Supramolecular, low-melting (near or below 0.0 °C) ionic liquid crystals with two rings of Schiff bases were prepared and studied. The Schiff bases were synthesized using 4-substituted aniline derivatives and 4-pyridine carbaldehyde and then mixed in equimolar amounts with linear 1-bromoalkanes of different chain lengths, namely C6, C8, and C14. The mesomorphic behavior and thermal properties of the compounds were determined by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). Only the ionic liquids analogous with 1-bromotetradecane exhibit mesomorphic behavior. All, except the smectic A (SmA) monomorphic fluorine-substituted complex, show dimorphic enantiotropic mesophases, namely SmA followed by nematic (N) mesophases depending on the temperature rise. The DSC and POM results for the induced mesophases were then treated with density functional theory calculations (DFT). The results showed that both the polarity of the polar groups and the length of the alkyl groups strongly influence the mesomorphic properties of the ionic liquids.
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