الفهرس 
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Abstract
The current study aim to investigate the reaction of ligand 6,6’(([1,1’biphenyl]4,4’diylbis(azaneylylidene))bis (methaneylylidene))bis(2,4-dichlorophenol (H2L) with the some transition metal ions such as Co(II), Ni(II) and Cu(II) and with some metal hexacarbonyls M(CO)6 (M= Cr, Mo and W).
Schiff base ligand (H2L) and its complexes are characterized by elemental analysis, spectroscopic studies such as IR, UV-vis, 1H NMR, mass, molar conductance, magnetic susceptibility measurements and thermal analysis.
Three complexes with molecular formulas [Co2(H2L)(H2O)4Cl4], [Ni2(H2L)(H2O)4Cl4] and [Cu2(H2L)2Cl4].3H2O are isolated from the reaction of metal ion with H2L. The ligand acted as tetradentate in all prepared complex. Conductance data shows that all the metal ion complexes are non-electrolytes.
The IR spectrum of ligand exhibits characteristic bands due to OH, (C-O) and azomethine group (C=N). The band of azomethine is shifted in the spectra of complexes to lower frequencies due to complex formation. Non-ligand phenolic group oxygen atom and the azomethine group nitrogen to the complex metal.
The 1H NMR of ligand displays singlets corresponding to OH phenol and azomethine (CH=N) groups. The 1H NMR of its metal ion complexes gave no signals indicating paramagnetic characteristics. The magnetic moment values (μeff) for the complexes Co(II), Ni(II) and Cu(II) suggested the octahedral structure of the complexes.
The electronic spectra of the complexes showed remarkable shift in π π* and n π* to lower or higher energy areas compared to the free ligand. The electronic spectra of the complexes also show new bands relationdue to d-d transitions.
Thermogravimetric analysis (TG and DTG) studies have shown the high thermal stability of the complexes and have confirmed the molecular formulas of the complexes.
The activation thermodynamic parameters, such as activation energy, enthalpy, entropy and Gibbs free energy change of decomposition are calculated using Coats–Redfern and Horowitz–Metzger methods.
Geometry of ligand and its metal ion complexes are optimized by gaussian 09 software. The bond length, bond angles, total energy, HOMO-LUMO energy gap and quantum chemical parameters are calculated from the optimized structures by density functional theory method.
The fluorescence spectra results revealed that the fluorescence emission intensity of the complexes decrease comparing to free ligand. Therefore, these compounds can potentially serve as photoactive materials as indicated from their characteristic fluorescence properties.
The catalytic activities of the Co(II), Ni(II) and Cu(II) complexes towards degradation of methylene blue dye in percent and absence of hydrogen peroxide by using two concentration of MB dye (9 ppm, 11 ppm) are studied. Also, measuring the activity of complexes on degradation of MB in percent of hydrogen peroxide at three temperatures 40, 50 and 60 ˚C.
The adsorption of Co2+, Ni2+ and Cu2+ in aqueous solution of H2L ligand under various conditions are studied. After 5 h the maximum adsorption percentage of Co(II), Ni(II), and Cu(II) ions are found to be 84, 75 and 86 %, respectively. Therefore, the removal percentage of metal ions increases by increasing time and decreasing the concentration of metal ion solution.
The Schiff base ligand and its metal ion complexes are examined for two Gram-positive, two Gram- negative bacteria species and two local fungal species.
In vitro anticancer properties of ligand (H2L) and its complexes [Co2(H2L)(H2O)4Cl4], [Ni2(H2L)(H2O)4Cl4] and [Cu2(H2L)2Cl4].3H2O against HepG-2 are investigated. The results show that the Cu(II) complexes could be moderate antitumor agent while ligand ,Co(II) and Ni(II) could not be considered as antitumor drugs.
The optical band gap values of the isolated complexes indicated semi-conductivity nature of these compounds and lie within the same range of highly effective photovoltaic materials.
The solid metal carbonyl complexes also prepared by reaction of M(CO)6 [M= Cr, Mo and W] with the Schiff base ligand H2L forming the complexes [Cr2(CO)L2], [Mo2O4L2] and [W2O4L2] which isolated under sunlight irradiation. In the air, the corresponding reaction resulted in the formation of the binuclear carbonyl oxo complex, [Mo2O5(CO)L].H2O. The ligand acted as tetradentate where it coordinated to metal through its nitrogen of azomethine and phenolic group.
The IR spectra of corresponding complexes [Cr2(CO)L2], [Mo2O4L2], [Mo2O5(CO)L].H2O and [W2O4L2] exhibited shifts in ʋ (HC=N) and ʋ (C-O) with respect to that of the free ligand. Also, the band of OH phenol in free ligand is disappeared. The IR spectrum of chromium complex shows strong band at 1718 cm−1 due to bridging carbonyl group. On the other hand, the IR spectrum of [Mo2O5(CO)L].H2O complex displays two bands at 1718 and 627 cm-1 due to bridging carbonyl group and Mo-O-Mo bridged bond, respectively. Also, the IR spectrum of complex [Mo2O5(CO)L].H2O shows stretching frequencies of hydrated water and terminal Mo=O bonds for a cis MO2 fragment. Both oxo complexes [Mo2O4L2] and [W2O4L2] are showed in the IR spectra two-terminal Mo=O vibrations at 915-906 cm-1 and 886-937 cm-1, respectively.
The 1H NMR spectra of the [Mo2O4(L)2], [Mo2O5(CO)L].H2O and [W2O4(L)2] complexes show downfield shift in the position of the azomethine proton (–HC=N) in comparison with that of the free ligand due to its coordination to metal atom through the azomethine nitrogen. In addition, the 1H NMR spectra of the molybdenum and tungsten complexes show disappearance of the hydroxyl proton signal indicating that the ligand coordinated to the metal with proton displacement. The 1H NMR spectrum of [Mo2O5(CO)L].H2O complex displays signal attributed to two protons of hydrogen which assigned to one molecule of water.
The magnetic study of the chromium complex reveals paramagnetic properties. The effective magnetic (μeff) value of 2.93 BM is close to the spin-only magnetic moment of two unpaired electrons (2.84 BM) in a low spin electronic configuration. Each chromium atom is existed in +2 oxidation state.
Thermal studies indicated a high thermal stability of all the complexes. The decomposition mass losses of the complexes are found to be in accordance with the molecular weight of each complex proposed from the elemental analysis.
The activation thermodynamic parameters are calculated graphically via two methods, Coats-Redfern and Horowitz- Metzeger methods.
The UV-Vis spectra of [Cr2(CO)2(L)2] and [W2O4(L)2] show Hypsochromic shifts in the π → π∗ and n→ π∗ electronic transitions by comparison with free ligand. In the spectra of complexes [Mo2O4(L)2] and [Mo2O5(CO)L].H2O, a bathochromic shift in electronic transitions in the π→π* was detected. while the n→π* bands observed hypsochromic shift with a significant change in absorbance.
the photoluminescence examination of complexes is studied. The emission bands of all complexes display a blue shift compared to that of the free ligand. Therefore, can potentially serve as photoactive materials.
The electrolytic nature of [Cr2(CO)2(L)2], [Mo2O4(L)2], [Mo2O5(CO)L]. H2O and [W2O4(L)2] complexes show that the synthesized complexes could be used as potential materials in solar cell systems due to their semiconducting propertie