Mohamed Gehad G
Chemistry Department, Faculty of Science, Cairo University, Giza, Egypt.
Spectrochim Acta A Mol Biomol Spectrosc. 2006 May 1;64(1):188-95. doi: 10.1016/j.saa.2005.05.044. Epub 2006 Mar 30.
Metal complexes derived from 2,6-pyridinedicarboxaldehydebis(p-hydroxyphenylimine); L1, 2,6-pyridinedicarboxaldehydebis (o-hydroxyphenylimine); L2, are reported and characterized based on elemental analyses, IR, solid reflectance, magnetic moment, molar conductance and thermal analysis (TGA). The complexes are found to have the formulae [MX2(L1 or L2)] x nH2O, where M=Fe(II), Co(II), Ni(II), Cu(II) and Zn(II), X=Cl in case of Fe(II), Co(II), Ni(II), Cu(II) complexes and Br in case of Zn(II) complexes and n=0-2.5. The molar conductance data reveal that the chelates are non-electrolytes. IR spectra show that the Schiff bases are coordinated to the metal ions in a terdentate manner with NNN donor sites of the pyridine-N and two azomethine-N. From the magnetic and solid reflectance spectra, it is found that the geometrical structure of these complexes are trigonal bipyramidal (in case of Co(II), Ni(II), Cu(II) and Zn(II) complexes) and octahedral (in case of Fe(II) complexes). The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the coordinated water, anions and ligands (L1 and L2) in the subsequent steps. The activation thermodynamic parameters, such as, E*, DeltaH*, DeltaS* and DeltaG* are calculated from the TG curves using Coats-Redfern method. The synthesized ligands, in comparison to their metal complexes also were screened for their antibacterial activity against bacterial species, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Fungi (Candida). The activity data show that the metal complexes to be more potent/antibacterial than the parent organic ligands against one or more bacterial species.
报道了由2,6 - 吡啶二甲醛双(对 - 羟基苯基亚胺)(L1)、2,6 - 吡啶二甲醛双(邻 - 羟基苯基亚胺)(L2)衍生的金属配合物,并通过元素分析、红外光谱、固体反射光谱、磁矩、摩尔电导率和热分析(热重分析)对其进行了表征。发现这些配合物的化学式为[MX2(L1或L2)]·nH2O,其中M = Fe(II)、Co(II)、Ni(II)、Cu(II)和Zn(II),对于Fe(II)、Co(II)、Ni(II)、Cu(II)配合物,X = Cl,对于Zn(II)配合物,X = Br,n = 0 - 2.5。摩尔电导率数据表明螯合物是非电解质。红外光谱表明席夫碱以三齿方式与金属离子配位,吡啶 - N的NNN供体位点和两个甲亚胺 - N参与配位。从磁性和固体反射光谱发现,这些配合物的几何结构为三角双锥(对于Co(II)、Ni(II)、Cu(II)和Zn(II)配合物)和八面体(对于Fe(II)配合物)。这些螯合物的热行为表明,水合配合物在第一步失去水分子,随后紧接着在后续步骤中配位水、阴离子和配体(L1和L2)分解。使用Coats - Redfern方法从热重曲线计算活化热力学参数,如E*、ΔH*、ΔS和ΔG。还对合成的配体及其金属配合物针对细菌物种大肠杆菌、铜绿假单胞菌、金黄色葡萄球菌和真菌(白色念珠菌)进行了抗菌活性筛选。活性数据表明,金属配合物对一种或多种细菌物种的抗菌活性比母体有机配体更强。