Synthesis, Characterization, and Study of Liquid Crystals Properties of New Five Heterocyclic Compounds

Authors

Adiba K. Amine Department of Chemistry, College of Education for Pure Science (Ibn-Al-Haitham), University of Baghdad, Baghdad, Iraq. https://orcid.org/0000-0002-5470-5503
Nisreen H. Karam Department of Chemistry, College of Education for Pure Science (Ibn-Al-Haitham), University of Baghdad, Baghdad, Iraq. https://orcid.org/0000-0003-0319-7446

DOI:

https://doi.org/10.30526/38.2.3354

Keywords:

Heterocyclics, Isotropic, Liquid crystal, Mesomorphic, Thiazolo[4,3-b][1,3,4] thiadiazol

Abstract

This work includes the synthesis and characterization of new compounds that contain 5H-thiazolo[4,3-b][1,3,4] thiadiazol united in multiple steps, starting with the synthesis of the aldehyde compound [I] by reaction chloro ethyl acetate with 4-hydroxybenzaldehyde in the presence of ethanol and potassium carbonate, followed by reactions with thiosemicarbazide, mercapto acetic acid in sulphuric acid to produce compound [II] then reflux compound [II] with hydrazine hydrate to product compound [III], after that reaction the later compound with n-alkoxybenzaldehyde [IV]_n and a few drops of piperidine in THF as a solvent to produce new Schiff᾽s-bases compounds contain 5H-thiazolo [4,3-b] [1,3,4] thiadiazol unite [V]n, FTIR and 1HNMR spectroscopy were used to analyze the compounds, a polarized optical microscope (POM) and differential scanning calorimetry (DSC) were used to examine the characteristics of the liquid crystals. In the Smectic A (SmA) and nematic phases, liquid crystal characteristics are present in all compounds [V]n. In addition to the nematic phase, all compounds [V]_n showed enantiotropic dimorphism in the SmA phase. It was discovered that compounds [V]_n with 5H- thiazole [4,3-b] [1,3,4]thiadiazol unit, the rigid-rod core of Schiff bases, and the formation of a supramolecular hydrogen bond between the derivatives [V]_n had liquid crystallinity, depending on the chain length of the alkoxy group as a terminal substituent.

Author Biographies

Adiba K. Amine, Department of Chemistry, College of Education for Pure Science (Ibn-Al-Haitham), University of Baghdad, Baghdad, Iraq.

Department of Chemistry, College of Education for Pure Science (Ibn-Al-Haitham), University of Baghdad, Baghdad, Iraq.
Nisreen H. Karam, Department of Chemistry, College of Education for Pure Science (Ibn-Al-Haitham), University of Baghdad, Baghdad, Iraq.

Department of Chemistry, College of Education for Pure Science (Ibn-Al-Haitham), University of Baghdad, Baghdad, Iraq.

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