الفهرس 
Literature surveyOnly 14 pages are availabe for public view
 |  | from | 186 |  |  |
| | | from | 186 | | |
Abstract
The present thesis includes three main chapters; introduction, literature survey, experimental, results and discussion as well as English and Arabic summary. 1- The first chapter of this thesis includes a literature survey of the previous work carried out on spectral studies of different azo dyes and their complexes. It also includes the different spectrophotometric methods for the microdetermination of some metal ions using a variety of azo dyes as chromogenic reagents. 2- The experimental part of the thesis ”chapter 2” includes the materials and reagents used as well as the experimental techniques. It comprises details concerning the materials, preparation of the azo dyes under investigation and some solid complexes, solutions, instruments used, working procedures and methods of calculation. The elemental analysis of the prepared azo dyes is also included. 3- Chapter 3 includes the results obtained and their discussion. It involves three main parts: Part one includes: a- The electronic spectral studies of azo dyes under investigation in ethanol and band assignment, the electronic spectra of azo dyes in some organic solvents of different polarities and the variation of CT band position is interpreted and related to the microscopic and macroscopic solvent parameters. The spectral behaviour of azo dyes in universal buffer of different pH values is studied and the pKa values of these azo dyes are determined using four different spectrophotometric methods. b- The IR spectra of azo dyes under investigation are discussed and their characteristic bands are assigned to the corresponding vibrational modes. Part two comprises : The results of an investigation of the reaction of sc3+, y3+, La3”, Gd3’, 2+ 1n3+, 2r02’ and U02 ions with azo dyes (I-V) in solution and includes the following points: a) The effect of pH, wavelength, sequence of addition, time and temperature on the colour development of the metal chelates is studied. b) The stoichiometries of the formed complexes are determined using different spectrophotometric methods (molar ratio, continuous variation and logarithmic form of the straight-line methods). c) The stability constants and the fiee energy changes of the formed complexes are calculated from the data obtained form the spectral results. d) The influence of forgein ions on the absorption spectra of the metal chelates is studied. e) Obeyence to Beer’s law for the metal chelates, Ringbom plots and spectrophotometric EDTA titrations of sc3+, y3+, La3+, Gd3+, h3’, zro2+ and U02 2’ ions using the azo dyes under investigation as indicators are discussed. f) Application for using the azo dyes under investigation as clu-omogenic reagents for the spectrophotometric determination of small amounts of sc3’, y3+, ~ a ~ + , ~ d ~ ’ , In3’, 2r02+ and U02 2’ ions in synthetic samples. Part three includes: Studies of the solid complexes, which includes: a) The chemical formula of the solid chelates are determined using the data obtained from the elemental analysis and molar conductance measurements as well as thermal methods of analysis (TGA and DTA). b) The IR spectra of the metal chelates are studied and compared with those of the free azo dyes which indicate that the metal ions are bounded to the ligands through the N=N and OH groups. c) The electronic absorption spectra of the solid chelates are studied and the characteristic bands are determined. The thesis ends with Arabic summary and list of references, which were of help during the study.