Synthesis and Mesomorphic and Electrical Investigations of New Furan Liquid Crystal Derivatives

Laila A Al-Mutabagani; Latifah A Alshabanah; Sobhi M Gomha; Tariq Z Abolibda; Mohamed Shaban; Hoda A Ahmed

doi:10.3389/fchem.2021.711862

Synthesis and Mesomorphic and Electrical Investigations of New Furan Liquid Crystal Derivatives

Front Chem. 2021 Sep 16:9:711862. doi: 10.3389/fchem.2021.711862. eCollection 2021.

Authors

Laila A Al-Mutabagani¹, Latifah A Alshabanah¹, Sobhi M Gomha^{2

3}, Tariq Z Abolibda³, Mohamed Shaban^{4

5}, Hoda A Ahmed^{2

6}

Affiliations

¹ Department of Chemistry, College of Science, Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia.
² Department of Chemistry, Faculty of Science, Cairo University, Cairo, Egypt.
³ Chemistry Department, Faculty of Science, Islamic University of Madinah, Al-Madinah, Al-Munawwarah, Saudi Arabia.
⁴ Nanophotonics and Applications Labs, Department of Physics, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt.
⁵ Department of Physics, Faculty of Science, Islamic University in Almadinah Almonawara, Medina, Saudi Arabia.
⁶ Chemistry Department, College of Sciences, Yanbu, Taibah University, Yanbu, Saudi Arabia.

Abstract

New homologues set liquid crystalline materials, based on furfural derivatives, namely, (E)-4-((furan-2-ylmethylene)amino)phenyl 4-alkoxybenzoate (F n), were synthesized and investigated for their mesomorphic and optical characteristics. The prepared homologues series constitutes three derivatives that bear different terminal flexible alkyl chain lengths that vary between 6 and 12 carbons and attached to the phenyl ring linked to the ester group. A furfural moiety is introduced into the other terminal of the molecular structure. Mesomorphic characterizations of the prepared derivatives were measured using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Molecular structures were elucidated via elemental analyses, FTIR, and NMR spectroscopy. DSC and POM showed that all the synthesized furfural derivatives are purely nematogenic, exhibiting an enantiotropic nematic (N) mesophase, except for the longest chain derivative (F 12) that is dimorphic possessing a monotropic smectic A phase and an enantiotropic N mesophase. Results indicated that the incorporation of the heterocyclic furfural ring into the molecular skeleton affected both the mesophase range and stability of investigated homologue. Analysis of the optical properties revealed that the shortest chain compound (F 6) possesses two direct band gaps, at 2.73 and 3.64 eV, in addition to higher absorption than the higher homologues, F 10 and F 12. On the other hand, all the synthesized homologues (F n) showed Ohmic behaviors, with electric resistances in the GΩ range. The values of the electrical resistances are 103.71, 12.91, and 196.85 GΩ at 0.05 V for F 6, F 10, and F 12, respectively.

Keywords: Schiff base/ester; electrical properties; furan liquid crystals; mesophase stability; optical properties.