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Abstract Semicarbazone ligands can be used to synthesise metal complexes with a wide range of structures and applications due to their ability to coordinate in either neutral or anionic state. In order to create novel molecules with interesting pharmacological properties, some metal complexes based on semicarbazone ligands can exhibit anticancer, antibacterial, and other biological activities. There is not any previous work described the metal complexes with semicarbazone of pyrano[3,2-c]quinolines moieties, therefore, the object of the present Thesis is to synthesis semicarbazone of 6-ethyl-4-hydroxy-2,5-dioxo-5,6-dihydro-2Hpyrano[ 3,2-c]quinoline-3-carboxaldehyde, H2L, ligand and study its chelating behavior towards copper(II), manganese(II), cobalt(II), nickel(II), zinc(II), cadmium(II), chromium(III), iron(III), oxovanadium(IV) and dioxouranium(VI) ions in a molar ratio (1:1, ligand: metal ion). The H2L ligand was prepared and elucidated by elemental analysis, IR, 1H-NMR, 13C-NMR, mass and electronic spectra. The newly prepared metal complexes of the present ligand were identified by elemental analyses, infrared, electronic, mass, 1H-NMR, 13C-NMR and ESR spectra as well as magnetic susceptibility measurements, molar conductance and thermal gravimetric analysis (TGA). The obtained results showed that the ligand behaves as dianionic O2N tridentate forming chelates with molar ratio 1:1, Summary ii (M:L) in all complexes and coordinates through enolate oxygen, azomethine nitrogen and deprotonated OH group. The absorption and fluorescence characteristics of the H2L and some of its metal complexes were recorded in nine different solvents with gradual increasing polarities at room temperature. The solvent effects on the fluorescence spectra of the prepared compounds showed solvatochromic behavior. The ground and excited state dipole moments of the H2L and some of its metal complexes were determined experimentally by solvatochromic shift method using Bilot–Kawski, Lippert–Mataga, Bakhshiev, Kawski–Chamma–Viallet and Reichardt’s microscopic solvent polarity functions and compared with those values obtained by TD-DFT (B3LYP/ GENECP) method. The large difference in dipole moments between electronically ground and excited states were found. Hence, the singlet excited state of the present molecules in polar solvent was more stabilized than the ground state. All complexes exhibited octahedral geometry except UO2(VI) complex exhibited pentagonal bipyramidal geometry. In the infrared spectra, it was found that the stretching frequency of C=Nazomethine, in all complexes was shifted to lower values in the range 1582-1571 cm-1. Also, the 1H-NMR spectra of diamagnetic Zn(II), Cd(II) and UO2(VI) complexes showed the disappearance of OH and NH protons which observed in the free ligand, indicating the presence of the ligand in the enol form during chelation, as well as the Summary iii participation of the ligand to metal ion through the phenolic and amidic oxygen atoms. To understand the nature of bonding of H2L ligand to metal ions; DFT calculations were performed using Gaussian 09 program. All theoretically probable structures of the free ligand (H2L) and its complexes have been calculated using B3LYP/GENECP basis set for C, H, N and O atoms and SDD basis set for the metal atom in gas phase to search for the most probable model building stable structure. Investigation of the structural parameters data and their correlations refers the following points: 1. The calculated dipole moment, EHOMO, ELUMO and Egap of the free ligand conformers, predicted the more favorable tautomeric form of the ligand. 2. ΔEgap of all complexes are smaller than that of their free ligand, indicates that the reactivity of complexes is higher than free ligand. 3. Generally, bond lengths of coordinating centers are longer than the corresponding in the free ligand (C=Nazomethine, C-Ophenolic and C-Oquinoline). Summary iv The H2L ligand and its metal complexes were screened for their antimicrobial activity against Staphylococcus aureus and Bacillus subtilis as Gram-positive bacteria, Escherichia coli and Salmonella typhimurium as Gram-negative bacteria, Candida albicans as yeast and Aspergillus fumigatus as fungal strains. The antitumor activity of the H2L ligand and its metal complexes were investigated against hepatocellular carcinoma cell line (HepG-2) in comparison with the standard antitumor drug Cisplatin. The tested complexes revealed variable activity towards the used cell. Docking investigations on the H2L ligand and current complexes revealed that they all significantly inhibited the VEGFR- 2 enzyme. The geometrical structures of the current complexes are shown below. |