الفهرس 
General IntroductionOnly 14 pages are availabe for public view
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Abstract
Schiff bases are considered as a very important class of organic compounds because of their ability to form stable complexes with many different transition metal and rare-earth metal ions in various oxidation states. They are used as inhibitors to reduce corrosive attack of the acid solutions on metallic material. In addition, the complexes of Schiff bases have wide applications in some biological aspects and fluorescence properties.
Due to the importance of the Schiff bases and their complexes, the present study intended to investigate the reactions of metal ions: Cu(II), Ni(II), Fe(III), Co(II), Zn(II), Hg(II), La(III) and Sm(III) with two Schiff bases derived from 2-furancrboxaldehyde and o-aminobenzoic acid (HL1) or O-phenylenediamide (L2).
The two Schiff base ligands and their complexes were prepared and characterized by elemental analyses, IR, 1H NMR, Uv-vis, fluorescence, mass spectroscopy, magnetic moment, molar conductance, and thermal analyses.
The first part of this study is directed to investigate the reactions of the metal ions with Schiff base HL1. The molar conductivities of the complexes indicated non-electrolytic behavior. The IR spectra of the complexes showed characteristic bands due to (C=N), (OH) and (C-O-C) with respect to that of the free ligand suggesting the coordination of metal ion through nitrogen atom of azomethine group, oxygen atom of carboxylate group and oxygen of furan moiety. Also, IR spectra of La(III) Sm(III) complexes showed that nitrate and perchlorates groups coordinated to metal in a bidentate manner. The 1H NMR spectra of the Zn(II), Hg(II) and La(III) complexes exhibited OH signal indicating the coordination of carboxylate to metal without proton displacement.
The measured value of the magnetic moment for complexes lies in the range reported for octahedral complexes. The diffuse reflectance spectra of the Cu(II), Ni(II), Co(II) and Fe(III) showed d-d electronic transitions suggesting octahedral structure around metal ions, while, these transitions are not expected for Zn(II) (d10), Hg(II) (d10), La(III) (d0) and Sm(III) (f5) complexes.
The other part of the thesis deals with the reactions of metal ions with the Schiff base L2. The molar conductivity measurements of metal complexes suggested the presence of a non-electrolytic nature except La(III) and Sm(III) complexes. The IR spectra of all complexes exhibited a broad band due to (OH) of crystalline or coordinated water molecules associated with the complex. The IR spectra of Zn(II) and Hg(II) complexes showed that the acetate groups coordinated to metal ion in a bidentate manner. Also, the spectra of La(III) and Sm(III) complexes indicated the ionic nature of the NO3− and ClO4− ions, respectively. The 1H NMR spectra of Ni(II), Zn(II), Hg(II) and La(III) complexes showed signals indicating their diamagnetic properties. The electrical conductance values of La(III) and Sm(III) complexes indicated the ionic nature of these complexes. The µeff = 1.98 B.M. of the Cu(II) complex indicated a square planar geometry. The diffuse reflectance spectrum of the Ni(II) complex showed three absorption bands characteristic for square planar geometry. The diffuse reflectance spectra of Co(II) and Fe(III) complexes suggested octahedral structure around metal ions.
The fluorescence spectral results revealed that the fluorescence emission intensity of Schiff bases increases dramatically on complexation with the reported transition metal ions. Therefore, all synthesized compounds can potentially serve as photoactive materials as indicated from their characteristic fluorescence properties.
Thermal studies indicated high stability of complexes. The kinetic and thermodynamic activation parameters of decomposition process of complexes namely activation energy, enthalpy, entropy and Gibbs free energy change of decomposition were evaluated graphically by employing the Coats-Redfern relation. The high activation energy values of the complexes revealed the high stability of the investigated complexes due to their covalent character.
The corrosion inhibition of stainless steel type 410 in 1M H2SO4 using the synthesized Schiff bases and their complexes as inhibitors considered these compounds as efficient corrosion inhibitors.
Furthermore, the novel complexes exhibited considerable antibacterial activity against Bacillus Subtilis (G+), Staphylococcus aureus (G+), Escherichia coli (G-) and Pseudomonas aeruginosa (G-), in comparison with the standard drug tetracycline.