الفهرس 
Introduction and aim of the present workOnly 14 pages are availabe for public view
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Abstract
Name: shabaan Ali kamel mohammed Elroby Title of the thesis: Theoretical and Experimental Investigation of the Electronic Structure and Spectra of Antitumor 2-(4-Aminophenyl)Benzothiazoles and Analogous. Degree: Ph.D. (Doctor of Philosophy in Chemistry) The present study presents a thorough analysis of the electronic structure and conformational preference of the antitumor 2-(4-aminophenyl)benzazoles and analogues. Thus, full-geometry optimization has been carried out for the studied series of compounds at the DFT B3LYP/6-311++G** level of theory. Geometric structural parameters and charge density distributions are computed, analyzed and discussed. The potential energy function for rotation about the C2-C1 bond has been computed for the studied series of compounds. Proton affinity on each of the possible sites in the antitumor 2-(4-aminophenyI)benzazoles and in their heterocyclic parent molecules, namely benzothiazole, benzoxazole, benzimidazole has been calculated at the B3LYP/6-311++G** level of theory in the gas phase and in solution. The potential energy surface (PES) for the protonation process was studied at DFT/ B3LYP/6-311++G** level of theory. The TDDFT/B3LYP-6-31G** and ZINDO/S methods have been used to compute and analyze the electronic spectra of benzazoles, 2-phenylbenzazoles and 2-(4-aminopheny)benzazoles. Comparison with the spectra of the corresponding benzazole and 2-phyenylbenzazole facilitates the understanding of the origin and the assignment of the observed band systems. Analysts of the charge density distributions and relative polarities of the ground and excited states enabled quantitative understanding of the observed solvent effects. Highly accurate ab initio molecular orbital computation has been performed to study the electronic structure and substituent effects on the singlet- triplet gaps of a series of nitrenium ions in the gas phase and in solution. DFT calculations at B3LYP/6-311++G** level predict that the nitrenium ions derived from the metabolism of antitumor 2-(4-aminophenyl)benzothiazoles exist as ground state singlet. The preferential stabilization of this state relative to the triplet is due to the transfer of charge density from the phenyl ring to formally electron deficient nitrogen atom. Quantitative structure-activity relationships (QSAR) have been established for two sets of the antitumor drugs, 2-(4-aminophenyl)benzothiazoIes (APBT). Constitutional, geometrical, topological, electronic descriptors (computed at B3LYP/6-311++G** level) and some empirical descriptors related to the hypophilicity were computed and analyzed. Key words: 1- DFT/B3LYP/6-311++G** 2- Barrier rotation 3- Proton affinities 4- Antitumor of 2-(4-Aminopheny)benzothiazoles 5- (S-T)gap 6- Benzazotes 7- ZINDO/S and TDD FT 8-Onsager, IPCM and PCM models 9- QSAR.