Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Physical Chemistry

5,7-diphenyl-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine and six of its derivatives are investigated experimentally and theoretically in Gas phase, Dioxane and DMF. The parent compound is investigated in details with its subsystems to predict the most active moiety responsible for the ground state properties of the parent compound and to study the different conjugation extends in the parent compound. The calculations of compounds 1-7 show that all the compounds are non-planar. The ground state properties of compounds 1-7 optimized at B3LYP/6-311G(df,pd) show that compound 2, which contains the nitro group, is the highest reactive compound, while compound 7 is the most polar one. The observed UV spectra in Dioxane and DMF of compounds 1-7 show that the difference in the spectral features of the studied compounds can be attributed to the extent of the hyper conjugation of the triazolo[1,5- a]pyrimidine moiety and the nature of the substituent of the two phenyl groups. Band maxima (n ) and intensities of the spectra are max found to have solvent dependence reflected as blue and red shifts. The theoretical spectra computed at TD-B3LYP/6-311G(d,p) in gas phase, Dioxane and DMF predict the electronic transition characters for the experimental bands observed. Biological activity calculated show no antifungal activity and a very weak antibacterial activity, where no noticeable relation can be found between the physical properties of the studied compounds and their biological activity.

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