الفهرس 
1. INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 216 |  |  |
| | | from | 216 | | |
Abstract
The Ph. D. thesis includes three main chapters
Aim of the work:-
The work aimed to prepare and characterize a new Schiff base ligand and its metal complexes aiming to study their effects on both microbial and corrosion of zinc which ligands and complexes acts as inhibitors for corrosion of zinc in medium of HCl.
I- Introduction
This chapter includes introduction to Schiff base and its types and nomenculture and an overview of the previous researches on complexes of Schiff base ligands and their applications and the corrosion inhibitors which uses some of ligands and complexes in the medium of corrosion to make inhibition for corrosion.
II- Experimental
This chapter contains the chemical reagents and equepiments used for measurement of different parameters all over the work as follow:
1) Preparation of the Schiff base ligands and its metal complexes.
2) characterization of the ligands and their complexes using different methods:
•Physical techniques such as molar conductances and magnetic susceptibility
•Elemental analyses (C, H, N, Cl and M).
•Spectral techniques as IR, (UV- Vis.), 1HNMR, mass spectra measurements.
3) Measurement of biological activity for the prepared complexes.
English Summary
- 188 -
4) Measurement of inhibition corrosion for the prepared complexes on zinc.
III- Results and discussion
This chapter includes characterization of the ligands and their complexes. The first ligand was prepared as follow:
1- Condensation of urea with dehydroacetic acid (1:1) for two hours to obtain the ligand.
(1E,3E)-1,3-bis(1-)6-methyl-2,4-dioxo-3,4-dihydro-2H-pyran-3-yl)ethylidene) urea ligand reacts with Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Mg(II), Fe(III) and Cr(III) ions to form octahedral or square plannar complexes. Their structures are characterized by elemental analyses, IR, Uv-Vis spectra , magnetic moments, molar conductances, 1H – NMR and mass spectra (ligand and its Zn(II) complex). The molar conductances of the complexes in DMF are commensurate with their non- ionic character. The ESR spectra of solid Cu(II) complexes show axial or isotropic type symmetry (dx2 – y2) ground state with covalent bond character. However, Co(II), Mn(II), Fe(III) and Cr(III) complexes show isotropic type. The invitro anticancer activity breast tumor cells and antifungal screening Aspergillus Niger fungi of some complexes have been investigated.
The second ligand was prepared as following :-
1- Condensation of thiourea with dehydroacetic acid (1:1) for two hours to give the ligand.
(Z)-1-(1-)6-methyl-2,4-dioxo-3,4-dioxo-2H-pyran-3(4H)-ylidene)ethyl) thiourea ligand reacts with Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) ion complexes of have been synthesized and characterized by elemental analyses, IR, UV- Vis, magnetic moments, conductances, mass spectra, 1H- NMR measurements. The IR spectral
data show that, the ligand behaves neutral, tetradentate or tetrabasic octadentate. Molar conductances in DMF solution indicate that, the complexes are non- electrolyte. Antimicrobial teste of the ligand and some complexes are also carried out and it has been observed that the complexes are more potent.
The corrosion inhibition of zinc in 2M HCl solution by thiourea , ligands , and complexes has been studied with respect to their concentrations. The corrosion rates were measured by using gasometric technique. The inhibition efficiency of each inhibitor increases and decreases with increasing its concentration in the range of inhibition action and missing inhibition action respectively. Zinc surface coverage (θ) could be obtained from the corrosion rates in 2M HCl solution in absence and presence the used additives by gasometric technique.
The inhibitors appear to function through adsorption following langmuir’s isotherm. The free energy change of adsorption (ΔGads.), enthalpy change (ΔHads.), entropy change(ΔS), and activation engry (Ea) associated with each inhibitor have been determined. The heat of adsorption (ΔHads.) and free energy of adsorption (ΔGads.) of all inhibitors are negative values.