The College of Education for Pure Sciences, Department of Chemistry, University of Basra, discussed a master’s thesis on the preparation and characterization of new compounds derived from benzothiazole and the study of the effect of terminal groups on their liquid crystalline properties.
The thesis presented by the researcher (Haider Abdel Salam Abdel Wahab) included a study of the preparation of ten compounds divided into two groups (B1Y) and (B2Z) from azobenzothiozole compounds, as all compounds of the two groups were substituted with different terminal groups in the bar site to clarify the effect of the terminal group on the liquid crystalline properties, The first group includes six compounds (B1H, B1CH3, B1OCH3, B1COCH3, B1Cl, B1NO2) that have the following general composition:
The second group included four compounds (B2H, B2CH3, B2OCH3, B2SCH3) that took the following general composition:
All prepared compounds were characterized by spectroscopic methods represented by (1H-NMR, 13C-NMR) spectra, mass spectra and infrared spectra. Liquid and isotropic. Polarized light microscopy was also used to diagnose the type of liquid crystal phases and their histological shapes. The results of this study showed that all compounds have intermediate liquid crystalline properties with two intermediate states, except for compound (B2H), in which no liquid crystal phase was diagnosed.
The prepared liquid crystalline compounds showed only the nematic phase with different thermal range as a result of the different end groups at one of its ends, and the nematic phase took the Marbled shape on heating and Schlieren shape on cooling.
A theoretical study was conducted for the second group prepared compounds in which the total dipole moment of the molecules, the lengths of the molecules, the bonds and the angle values were calculated, as well as the higher energy of occupied orbital (HOMO) and lower energy of unoccupied orbital (LUMO) and the difference between them (Energy gap ΔE) to support the interpretation of liquid crystalline properties.
Aim of the study:
Preparation and characterization of heterocyclic compounds derived from benzothiazoles and study of their liquid crystal properties.
Study of the effect of the type of the terminal group on the appearance of liquid crystal characteristics and their thermal stability.
Conducting a theoretical study to calculate the dipole moment, particle lengths, bonds, and angle values, to find out their agreement with our interpretation of the practical results.
