M.M. Omar

Biological activity studies on metal complexes of novel tridentate Schiff base ligand. Spectroscopic and thermal characterization

Metal complexes of novel Schiff base (HL) ligand, prepared via condensation of 4-aminoantipyrine and 2-aminophenol, are prepared. The ligand is characterized based on elemental analysis, mass, IR and (1)H NMR spectra. Metal complexes are reported and characterized based on elemental analyses, IR, (1)H NMR, solid reflectance, magnetic moment, molar conductance, ESR spectra and thermal analyses (TG, DTG and DTA). From the elemental analyses, 1:1 [M]:[ligand] complexes are prepared with the general formulae [M(L)Cl(H(2)O)(2)] x yH(2)O (M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II), y = 3-4), [Fe(L)Cl(2)(H(2)O)] x 3 H(2)O and [Th(L)Cl(H(2)O)(2)]Cl(2) x 3 H(2)O. The molar conductance data reveal that all the metal chelates are non-electrolytes (except Th(IV) complex, it is 2:1 electrolyte). IR spectra show that HL is coordinated to the metal ions in a uninegatively tridentate manner with NNO donor sites of the azomethine-N, amino N and deprotonated phenolic-O. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral. 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 anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters are calculated from the DTG curves using Coats-Redfern method. The synthesized ligand, in comparison to its metal complexes is screened for its antibacterial activity against bacterial species, Escherichia coli, Pseudomonas putida, Exiguobacterium acetylicum and Bacillus simplex. The activity data show that the metal complexes to be more potent/antibacterial than the parent Schiff base ligand against one or more bacterial species.

Synthesis, structural, thermal studies and biological activity of a tridentate Schiff base ligand and their transition metal complexes.

Schiff base (L) ligand is prepared via condensation of pyridine-2,6-dicarboxaldehyde with -2-aminopyridine. The ligand and its metal complexes are characterized based on elemental analysis, mass, IR, solid reflectance, magnetic moment, molar conductance, and thermal analyses (TG, DTG and DTA). The molar conductance reveals that all the metal chelates are non-electrolytes. IR spectra shows that L ligand behaves as neutral tridentate ligand and bind to the metal ions via the two azomethine N and pyridine N. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral (Cr(III), Fe(III), Co(II), Ni(II), Cu(II), and Th(IV)) and tetrahedral (Mn(II), Cd(II), Zn(II), and UO2(II)). 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 anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, ΔH*, ΔS* and ΔG* are calculated from the DTG curves using Coats-Redfern method. The synthesized ligand, in comparison to their metal complexes also was screened for its antibacterial activity against bacterial species, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus pyogones and Fungi (Candida). The activity data shows that the metal complexes to be more potent/antibacterial than the parent Schiff base ligand against one or more bacterial species.

Spectroscopic characterization of metal complexes of novel Schiff base. Synthesis, thermal and biological activity studies.

Novel Schiff base (HL) ligand is prepared via condensation of 4-aminoantipyrine and 2-aminobenzoic acid. The ligand is characterized based on elemental analysis, mass, IR and (1)H NMR spectra. Metal complexes are reported and characterized based on elemental analyses, IR, (1)H NMR, solid reflectance, magnetic moment, molar conductance and thermal analyses (TGA, DrTGA and DTA). The molar conductance data reveal that all the metal chelates are non-electrolytes. IR spectra show that HL is coordinated to the metal ions in a uninegatively tridentate manner with NNO donor sites of the azomethine N, amino N and deprotonated caroxylic-O. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral. 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 anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, DeltaH*, DeltaS* and DeltaG* are calculated from the DrTG 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 Pyogones and Fungi (Candida). The activity data show that the metal complexes to be more potent/antibacterial than the parent Shciff base ligand against one or more bacterial species.

Preparation, characterization and biological activity of novel metal-NNNN donor Schiff base complexes

Novel Schiff base (H(2)L) ligand is prepared via condensation of benzil and triethylenetetraamine. The ligand is characterized based on elemental analysis, mass, IR and (1)H NMR spectra. Metal complexes are reported and characterized based on elemental analyses, IR, (1)H NMR, solid reflectance, magnetic moment, molar conductance, and thermal analyses (TG, DTG and DTA). 1:1 [M]:[H(2)L] complexes are found from the elemental analyses data having the formulae [M(H(2)L)Cl(2)]xyH(2)O (M=Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II)), [Fe(H(2)L)Cl(2)]ClxH(2)O, [Th(H(2)L)Cl(2)]Cl(2)x3H(2)O and [UO(2)(H(2)L)](CH(3)COO)(2)x2H(2)O. The metal chelates are found to be non-electrolytes except Fe(III), Th(IV) and UO(2)(II) complexes are electrolytes. IR spectra show that H(2)L is coordinated to the metal ions in a neutral tetradentate manner with 4Ns donor sites of the two azomethine N and two NH groups. The geometrical structures of these complexes are found to be octahedral. The thermal behaviour of these chelates is studied where the hydrated complexes lose water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters are calculated using Coats-Redfern method. The ligand (H(2)L), in comparison to its metal complexes, is screened for its antibacterial activity. The activity data show that the metal complexes have antibacterial activity more than the parent Schiff base ligand and cefepime standard against one or more bacterial species.

Synthesis, spectral characterization, thermal, anticancer and antimicrobial studies of bidentate azo dye metal complexes

As a part of systematic investigation of biologically active compound, m-phenylene diamine, new azo dye ligand was synthesized by diazotization of m-phenylene diamine and coupled with coupling compound, p-methoxy benzaldehyde. A new series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes derived from this azo dye ligand (L) were synthesized. The structures of the ligand and metal complexes were confirmed by elemental analysis, spectroscopic studies (IR, UV–Vis, 1H NMR, mass spectrometry, electronic spectra, magnetic susceptibility and ESR), conductivity measurements, thermogravimetric analyses (TG-DTG) and X-ray powder diffraction. The molar conductance measurements of the complexes in DMF determine electrolytic nature of the complexes. On the basis of elemental and thermal analyses, magnetic moment, electronic and ESR spectral studies, an octahedral geometry was assigned for metal complexes. XRD data reflect that azo dye ligand and its Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes are amorphous while Cd(II) complex is crystalline. Also, the newly synthesized azo dye ligand, in comparison with metal complexes, is screened for its antimicrobial and anticancer activity against breast cancer cell line (MCF7). The results showed that Mn(II), Ni(II) and Zn(II) metal complexes have higher anti-breast cancer activity than free ligand.

Chelation behaviour of lanthanides with somethio-Schiff bases

SummaryThe stability constants of complexes of trivalent Y, La, Ce, Pr, Sm, Gd, Dy, Ho, Er, and Yb ions with somethio-Schiff bases have been determined potentiometrically using theCalvin-Bjerrum titration technique as modified byIrving andRossotti at 25 °C and an ionic strength of 0.1M (NaCl) in 70% (v/v) aqueous ethanol. 1:1 and 1:2 complexes are formed and evidenced by conductometric studies. ThepKa values of the SH group were correlated with theHammet constants of substituents. The values of the stability constants are correlated with the atomic numbers of the lanthanides and with the sum of the ionization constants of the ligands.ZusammenfassungDie Stabilitätskonstanten von Komplexen trivalenter Y-, La-, Ce-, Pr-, Sm-, Gd-, Dy-, Ho-, Er- und Yb-Ionen mit einigenthio-Schiffschen Basen wurden potentiometrisch unter Verwendung der vonIrving undRossotti modifiziertenCalvin-Bjerrum-Titrationstechnik bei 25 °C undI=0.1M (NaCl) in 70% (v/v) wäßrigem Ethanol bestimmt. Wie konduktometrisch gezeigt werden konnte, treten 1:1- und 1:2-Komplexe auf. DiepKa-Werte der SH-Gruppen wurden mit denHammetschen Substituentenkonstanten korreliert, die Stabilitätskonstanten mit den Kernladungszahlen der Lanthaniden und mit der Summe der Ionisationskonstanten der Liganden.

Potentiometric and thermogravimetric studies on some metal-oxine-sulphadrugs ternary complexes

Formation constants (logKMALMA) of the mixed complexes of the type M–A–L (where M=Mn(II), Co(II), Ni(II), Cu(II), Ce(III), Th(IV), and UO2(II); A=oxine and L=sulphamerazine or sulphadiazine) have been determined pH-metrically in 60% (v/v) ethanol–water mixture at 25°C and constant ionic strength (μ=0.1 M NaCl). The mode of chelation was ascertained by conductivity measurements. The stability sequence with respect to metal ions have been found to be Cu(II)>Ni(II)>Co(II)>Mn(II) and Th(IV)>UO2(II)>Ce(III). CuAL ternary solid complexes have been prepared and characterized on the basis of elemental analysis and IR-spectroscopy. The thermal degradations of the prepared complexes are discussed in an attempt to assign the intermediate compounds formed.

Synthesis, spectroscopic, thermal and biological activity studies on triazine metal complexes.

The coordination behaviour of the triazine ligand with NNO donation sites, derived from 3-benzyl-7-hydrazinyl-4H-[1,3,4]thiadiazolo[2,3c][1,2,4]triazin-4-one (HL), towards some metal ions namely Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) are reported. The metal complexes are characterized based on elemental analyses, IR, (1)H NMR, solid reflectance, magnetic moment, molar conductance and thermal analyses (TG, DTG and DTA). The ionization constants of the organic ligand under investigation as well as the stability constants of its metal chelates are calculated spectrophotometrically at 25°C. The chelates are found to have octahedral geometrical structures. The ligand (HL) and its binary chelates are subjected to thermal analyses (TG, DTG and DTA) and the different activation thermodynamic parameters are calculated from their corresponding DTG curves to throw more light on the nature of changes accompanying the thermal decomposition process of these compounds. The synthesized ligand and its metal complexes were found to have biological activity against the desert locust Schistocerca gregaria (Forsk.) (Orthoptera - Acrididae) and its adult longevities.

Synthesis, Spectroscopic, and Thermal Characterization of Thiazole Metal Complexes: Biological Activity Studies

Metal complexes of the organic ligand with N azomethine and N thiazole donation sites, derived from 3-(2-(2-(2,6-dichlorobenzylidene)hydrazinyl)-4-oxo-4,5-dihydrothiazol-5-yl) acetic acid (H2L), with some transition metal ions, namely Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II), are reported. They are characterized based on elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, and molar conductance. The ionization constants are found to be 5.57 and 11.50, which can be attributed to loss of the hydrazo and the carboxylic acid protons, respectively. The stability constants of metal chelates, is calculated spectrophotometrically at 25°C, and the order of stability follows the Irving and Williams order. The chelates are found to have octahedral geometrical structures. The ligand (H2L) and its binary chelates are subjected to thermal analyses, and the different activation thermodynamic parameters are calculated using Coats-Redfern equation. The ligand and its metal complexes show a remarkable biological activity against the desert locust Schistocerca gregaria (Forsk) (Orthoptera – Acrididae) and its adult longevities.

METAL CHELATES OF BENZIMIDAZOLYLAZO DERIVATIVES

SummaryThe complexation of 2-(4-benzimidazolylazo)-R-acid and 5-(4-benzimidazolylazo)-8-hydroxy-quinoline with Mn(II), Co(II), Ni(II), and Cu(II) have been studied potentiometrically using the Calvin-Bjerrum titration technique as employed by Irving and Rossotti. Protonation constants of the ligands and stability constants of the metal complexes have been determined at constant temperature (25|dgC) and ionic strength (0.1 µ NaCl). The order of stability constants (logβ1), Mn(II) < Co(II) < Ni(II) < Cu(II) is in conformity with the Irving-Williams order. The structures of the solid complexes have been assigned on the basis of elemental analysis and IR spectroscopy. Also conductimetric titrations have been made to characterize the composition of the complexes.ZusammenfassungEs wurde die Komplexierung von 2-(4-Benzimidazolylazo)-2-hydroxynaphthalin-3,6-disulfonsäure und 5-(4-Benzimidazolylazo)-8-hydroxychinolin mit Mn(II), Co(II), Ni(II) und Cu(II) potentiometrisch mittels der Calvin-Bjerrum-Titrationsmethode in der Modifikation von Irving-Rossotti untersucht. Die Protonierungskonstanten der Liganden und die Stabilitätskonstanten der Metallkomplexe wurden für eine Temperatur von 25|dgC und eine Ionenstärke von 0.1 µ (NaCl) bestimmt. Die Reihung nach Stabilitätskonstanten (log β1), Mn(II) < Co(II) < Ni(II) < Cu(II), ist in Übereinstimmung mit der Irving-Williams-Ordnung. Die Strukturen wurden mittels Elementar-analyse und IR-Spektroskopie charakterisiert. Zur Ermittlung der Zusammensetzung der gebildeten Komplexe wurden auch Leitfähigkeitsmessungen durchgeführt.