The College of Education for Pure Sciences, Department of Chemistry, reviewed a doctoral dissertation on "Preparation and Characterization of Benzothiazole and Oxazole Derivatives and Study of Their Liquid Crystalline Properties."

The study, presented by researcher Nizar Shatei Nweir, aimed to:

Prepare and characterize novel heterocyclic compounds derived from benzothiazole and study their liquid crystalline properties.

Investigate the effect of terminal group type on the appearance of liquid crystalline properties and thermal stability.

Study the effect of increasing terminal aliphatic chain length on the appearance of liquid crystalline phases and their thermal stability.

Prepare novel compounds with different substitution side groups and study the effect of these groups on liquid crystalline properties.

Determine the extent to which bonding groups, such as azomethine, azo, esters, and benzene rings, affect liquid crystalline properties. A theoretical study was conducted on the compounds of the first group only, calculating the total molecular dipole moment, length-to-width ratio, energy of the highest occupied molecular orbital (HOMO), energy of the lowest unoccupied molecular orbital (LUMO), and the difference between them (energy gap ΔE) to support the experimental results in studying the properties of liquid crystals.

The thesis included the study of the preparation of twenty-seven compounds belonging to four different groups, which can exist in more than one structural formula, as follows:

Group One: Preparation of six compounds with the following general structure:

To study the effect of para- and meta-substituted terminal groups on the liquid crystal properties.

Group Two: Thirteen compounds, including:

The compounds (F-SRn where n=1,2,4-8), (F-ORn where n=1,2,6), (Cl-SRn where n=1,4), and (H-SR4) have the following general structure:

To illustrate the effect of the terminal thioyl chain length on their liquid crystal properties, the difference in the effect of the oxygen and sulfur atoms on the liquid crystal properties, and the effect of the substituent groups at position (6) of the aromatic ring in the benzothiazole group

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