الفهرس 
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Abstract
The thesis entitled llPhysicochemical studies on metal complexes of some nucleic acid constituentsu comprises three chapters. The first includes mainly the literature survey on the structural chemistry of some pyrimidines and their complexes. The experimental part is given in the second chapter. The synthesis of both the free ligands and their complexes are described. The analytical data depict the formation of different complexes with the stoichiometries 1:2 and 1:3 (M : L) depending on the transition metal salt and the ligand. Different standardized instruments (’H-NMR, IR, W-Vis, magnetic susceptibility, Mossbauer spectra, ESR and thermal analysis) are used. The calculations have been carried out on PDP 11/70 computer at the Computer Center of Faculty of Scienck, Alexandria University, Egypt. The preparation of the solutions (ligands, buffers and the purification of solvents) are explained. The third chapter is related to the results and discussions. The ’H-NMR spectra of thiouracil and its 5- (substituted phenylazo) thiouracil compounds in d6-~~s0 solvent suggested their existence in the thione form. However citrazinic acid and its 5-(substituted pheny1azo)citrazinic acid compounds are in the keto-en01 forms. The IR spectra assigned the different modes of -iivibrations of the fundamental functional groups. Different types of hydrogen bonds with the suggestions of the phenomena of tautomerism are explained. The electronic absorption spectra of the citrazinic acid and its azo compounds in presence of’ different solvents are recorded. The data are analysed based on the multiple regression technique: y = a, + alxl + a,x, + . . . using a microstatic ,program on a PC computer to give different correlations. The properties of,the solvents: polarity, the solute permanent dipole-solvent permanent dipole, the intermolecular hydrogen bonding and the solute permanent dipole-solvent induced dipole interactions (symbolled K, N, E and M, respectively) are used to explain the spectra. Different equations are applied (one, two and three parameters) for the correlations. The data are deeply discussed in details and correlated with the molecular structure of the compounds, e.g. substituent effect, hydrogen bond. The experimental absorbance data of orotic acid and its azo at different pH1 s are analysed on PC computer using a Fortran program version (77) to calculate their dissociation constants using three statistical methods. va values of uracil, thiouracil, 5- (substituted phenylazo) uracil, 5- (substituted phenylazo)thiouracil, orotic acid, citrazinic acid and 5-(substituted pheny1azo)citrazinic acid in aqueous media at different temperatures (25-45OC) and in presence of 25%, 35%, 50% and 75% (v/v) ethanol-water media at (25--iii- 45OC) and dioxane-water media at (25OC) are evaluated by pH-measurements.