Mahmoud M. Mashaly

Mixed‐Ligand Complexes of a Schiff Base, 8‐Hydroxyquinoline and Oxalic Acid with Cu(II), Ni(II), Zn(II), and Fe(III) Ions: Pyrolytic Products and Biological Activities

Abstract Binary mononuclear complexes of the Schiff base ligand 1,4‐di(hydroxybenzylidene)thiosemicarbazide (H2L) and the transition metal ions Cu(II), Ni(II), Zn(II), and Fe(III) were prepared in the presence of various molar ratios of LiOH. The binary complexes react with 8‐hydroxyquinoline (8‐HOqu) and oxalic acid (H2Ox) to form mixed‐ligand complexes. The mixed ligand complexes were prepared by using various molar ratios of LiOH. The thermal studies explored the stability of the mixed‐ligands in their complexes as the isolated thermal products also contain the mixed ligands. All of the binary and mixed‐ligand complexes have octahedral configurations except [CuHL]Cl and [ZnL], which have square‐planar geometrics. The Schiff base ligand (H2L) is coordinated to the central metal atom as a neutral, monoanionic and/or dianionic tetradentate ONNO ligand in the binary complexes and in the mixed‐ligand complexes. The mixed‐ligand, 8‐HOqu behaves as a neutral or monoanionic bidentate ligand. The oxalato ligand coordinates as a dianionic bidentate or a bridged bidentate ligand towards Fe(III) ions. All complexes and the corresponding thermal products were isolated and their structures were elucidated by elemental analyses, conductance, IR and electronic absorption spectra, magnetic moments, 1H NMR and TG‐DSC measurements as well as by mass spectroscopy. The free ligand H2L and its metal complexes showed higher antibacterial activity than some of the investigated antibiotics, doxycillin, sulperazon, septrin, cefobid, nitrofurantion, and erythromycin.

Synthesis, characterization and thermal studies of binary and/or mixed ligand complexes of Cd(II), Cu(II), Ni(II) and Co(III) based on 2-(Hydroxybenzylidene) thiosemicarbazone: DNA binding affinity of binary Cu(II) complex

A new series of metal complexes of Cd(II), Cu(II), Ni(II) and Co(III) with Schiff base ligand, H(2)L, 2-(Hydroxybenzylidene) thiosemicarbazone were synthesized. The mixed ligand complexes were prepared by using glycine (Gly), 2-aminopyridine (2-Ampy) and 1,10-phenanthroline (Phen) as secondary ligands. The structure of these complexes was identified and confirmed by elemental analysis, molar conductivity, UV-Vis, FT-IR and (1)H NMR spectroscopy and magnetic moment measurements as well as TG-DSC technique. The discussions of the prepared complexes indicate that the ligand behaves as a monoanionic tridentate ligand through ONS donor sites. Thermal studies suggested a mechanism for the degradation of the metal complexes as a function of temperature supporting the chelation modes and showed the possibility of obtaining new complexes pyrolytically in the solid state which cannot be synthesized from the solution. The absorption studies support that the binary Cu(II) complex exhibits a significant binding affinity to HS-DNA through intercalative mode.

Synthesis and Physico-Chemical Studies on Rhenium(V) Complexes with 2-Benzimidazolethione

Abstract A new series of rhenium(V) complexes were prepared by the reaction of 2-benzimidazolethione with H2[ReOCl5]. Mononuclear complexes of different types, such as [ReOLCl3(OH2)], [ReOL2(OH2)3]Cl3 and [ReOLCl(OH2)3]Cl2, and dinuclear complexes, such as [Re2O3L2Cl4].2H2O and [Re2O2L3Cl6].2H2O, where L = 2-benzimidazolethione were obtained depending on the metal: ligand molar ratio and the concentration of hydrochloric acid containing the starting rhenium complex. The electronic absorption spectra and magnetic moments of the complexes show that they have octahedral configurations. IR and conductivity measurements combined with thermal analyses show that the ligand behaves as a neutral, mono-or bidentate ligand towards the metal atoms.

Copper(II), Nickel(II), Oxovanadium(IV) and Dioxouranium(VI) Complexes of Novel Asymmetric Tetradentate Schiff Base Ligands Derived from 6-Methyl-3-Formyl-4-Hydroxy-2-(1H)-Quinolone. Part V

Abstract The novel, half-unit ligand obtained by the single condensation of 6-methyl-3-formyl-4-hydroxy-2-(1H)-quinolone and p-phenylenediamine, was condensed with either acetylacetone or salicylaldehyde to yield novel, asymmetric tetradentate Schiff base ligands, H2La and H2Lb, respectively. The reactions of the ligands with Cu2+, Ni2+, VO2+ and UO2 2+ salts yielded complexes of the general formula [L2M2 nH2O, except that of the uranyl complex of the ligand H2La which has the formula [LaUO2)2(OAc)2(OH2)2]. The ligands and metal complexes were characterized by elemental analyses, IR, UV-visible, mass and ESR spectra and magnetic measurements. The Cu2+ complexes are distored tetrahedral, the Ni2+ complexes are octahedral, the VO2+ complexes are square pyramidal and the UOz z+ complexes are pentagonal bipyramidal The vanadyl and nickel complexes showed antiferromagnetic interaction between adjacent metal cations.

PREPARATION AND THERMAL STUDIES OF SOME NEW OXORHENIUM(V) COMPLEXES WITH 2-AMINO-5-METHYL-1,3,4-THIADIAZOLE

ABSTRACT A new series of oxorhenium(V) complexes were prepared by the reaction of 2-amino-5-methyl-1,3,4-thiadiazole (L), alone or with addition of NaSCN, with H2[ReOCl5]. Mononuclear complexes of various types, [ReOLCl3- (OH2)], [ReOL2Cl2(OH2)]Cl, [ReOLCl(SCN)2(OH2)], [ReOL2Cl3] and [ReOLCl2(SCN) (OH2)], along with binuclear complexes, Re2O2(µ-L)Cl6(OH2)2·2H2O and [Re2O3(µ-L)Cl4]·2H2O, were obtained depending on the metal:ligand molar ratio and the concentration of hydrochloric acid containing the dissolved parent rhenium complex. Thermal studies on these complexes showed the possibility of obtaining new complexes pyrolytically, where the complexes decompose through several isolable as well as non-isolable, intermediates during heating. [Re2O3L4Cl4], [Re2O3(µ-L)2(SCN)4], [Re2O2(µ-L)(µ-Cl)2Cl4] and [Re2O3(µ-L)2(SCN)2Cl2, were synthesized pyrolytically in the solid state from the respective precursor rhenium complexes. All of the prepared complexes and their thermal products have octahedral configurations. The ligand (L) behaves in these complexes either as a neutral monodentate or bidentate ligand towards oxorhenium ions. The structures of all complexes and the corresponding thermal products were elucidated by elemental analyses, conductance, IR and electronic absorption spectra, magnetic moments, 1H NMR and TG-DSC measurements.

Heteronuclear complexes of oxorhenium(V) with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO2(VI) and their biological activities

Heteronuclear complexes containing oxorhenium(V), with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO2(VI) ions were prepared by the reaction of the complex ligands [ReO(HL1)(PPh3)(OH2)Cl]Cl (a) and/or [ReO(H2L2)(PPh3)(OH2)Cl]Cl (b), where H2L1 = 1-(2-hydroxyphenyl)butane-1,3-dione-3-(5,6-diphenyl-1,2,4-triazine-3-ylhydrazone) and H3L2 = 1-(2-hydroxyphenyl)butane-1,3-dione-3-(1H-benzimidazol-2-ylhydrazone), with transition and actinide salts. Heterodinuclear complexes of ReO(V) with Fe(III), Co(II), Ni(II), Cu(II) and Cd(II) were obtained using a 1 : 1 mole ratio of the complex ligand and the metal salt. Heterotrinuclear complexes were obtained containing ReO(V) with UO2(VI) and Cu(II) using 2 : 1 mole ratios of the complex ligand and the metal salts. The complex ligands a and b coordinate with the heterometal ion via a nitrogen of the heterocyclic ring and the nitrogen atom of the C=N7 group. All transition metal cations in the heteronuclear complexes have octahedral configurations, while UO2(VI) complexes have distorted dodecahedral geometry. The structures of the complexes were elucidated by IR, ESR, electronic and 1H NMR spectra, magnetic moments, conductance and TG-DSC measurements. The antifungal activities of the complex ligands and their heteronuclear complexes towards Alternaria alternata and Aspergillus niger showed comparable behavior with some well-known antibiotics.

Synthesis and Characterization of New Transition and Actinide Metal Complexes of a Hydrazone Ligand. Mixed‐Ligand Complexes, Pyrolysis Products, and Biological Activity

Abstract The chelating properties the hydrazone ligand 2‐carboxyphenylhydrazo‐ethylcyanoacetate (H2L) have been studied. A new series of binary mononuclear complexes were prepared from the reaction of the hydrazone ligand (H2L) with the metal ions, Cd(II), Cu(II), Ni(II), Co(II), Th(IV), and UO2(VI), in the presence of LiOH as a deprotonating agent. The binary Cu(II) complex of H2L was reacted with the ligands 1,10‐phenanthroline or 2‐aminopyridine to form mixed‐ligand complexes. The binary complexes of Cu(II) and Ni(II) are suggested to have octahedral configurations. The Cd(II) and Co(II) complexes are suggested to have tetrahedral and/or square‐planar geometries, respectively. The Th(IV) and UO2(VI) complexes are suggested to have octahedral and dodecahedral geometries, respectively. The mixed‐ligand complexes have octahedral configurations. Also, new complexes were obtained pyrolytically as the previous complexes decompose through several isolable as well as non‐isolable intermediates during heating. The structures of all complexes and the corresponding thermal products were elucidated by elemental analyses, conductance, IR and electronic absorption spectra, magnetic moments, 1H NMR and TG–DSC measurements, as well as by mass spectroscopy. The ligand and some of the metal complexes were found to activate the enzyme pectinlyase.

SYNTHESIS AND THERMAL INVESTIGATIONS OF 2-HYDRAZINO-BENZIMIDAZOLE COMPLEXES OF RHENIUM(V) IN THE SOLID STATE

Abstract A new series of rhenium(V) complexes was prepared by reaction of 2-hydrazinobenzimidazole (L), alone or mixed with KSCN, with H2[ReOCl5]. Mononuclear complexes of different tvpes, [ReOLCl(OH2)2]Cl2 2H20, [ReOL2(OH2)3]Cl3, [ReOLCl3(OH2)], [ReOL(SCN)2Cl(OH2)] 2H20 and [ReOL(SCN)Cl2(OH2)], along with dinuclear complexes, [Re203LCl4(OH2)2] - 2H2O and [Re2O3L2Cl2(OH2)4] Cl2, were obtained depending on the metal: ligand molar ratio and the concentration of hydrochloric acid containing the starting rhenium complex. These complexes decompose through several isolable, as well as non-isolable, intermediates during heating. [Re2O3L2Cl4], [ReOL2Cl] and [Re2O3L2(SCN)4], were synthesized pyrolytically in the solid state from the corresponding rhenium complexes. The electronic absorption spectra and magnetic moments prove octahedral configuration of the complexes. Conductivity measurements, IR and 1H NMR spectroscopy combined with thermal analyses, show that the ligand behaves as a neutral, mono- or bidentate l...

Spectral characterization, molecular modeling and antimicrobial studies on hydrazone metal complexes of 5-acetyl-4-hydroxy-2H-1,3-thiazine-2,6(3H)dione and S-methyl dithiocarbazate.

Metal complexes of copper(II), nickel(II), cobalt(II), oxovanadium(IV), chromium(III) and cadmium(II) with a new bridged ONS dibasic tridentate hydrazone (H2L) derived from 5-acetyl-4-hydroxy-2H-1,3-thiazine-2,6(3H)-dione with S-methyl dithiocarbazate have been synthesized and characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, spectral (infrared, electronic, mass, 1H NMR and ESR) studies as well as thermal gravimetric analysis (TGA). The synthesized complexes have dimeric structures with the general formula [ML(NO3)m(H2O)x]2·nH2O·zMeOH, L=dianion of the hydrazone, m=0-1, x=0-2, n=0-4 and z=0-1. The metal complexes exhibited square planar, tetrahedral and octahedral geometrical arrangements, the molar conductivity data indicates that all complexes are neutral. The Coats-Redfern equation was used to calculate the kinetic and thermodynamic parameters for the different thermal decomposition stages of some complexes. Structural parameters of the ligand and its metal complexes have been theoretically computed on the basis of semiempirical PM3 level and the results were correlated with their experimental data. Antibacterial activities of the free ligand and its metal complexes were screened against various organisms.

Synthesis and thermal studies of tetraaza macrocylic ligand and its transition metal complexes. DNA binding affinity of copper complex.

A Tetraaza Macrocylic Ligand (H2L) and its complexes, [Cd(H2L)(OH2)2](NO3)(2)·1/2OH2 (I), [Co(H2L)(OH2)](NO3)(2)·1/2OH2 (II), [Cu(H2L)(NO3)2]·3/2OH2 (III) and [Ni(H2L)(NO3)(OH2)]NO3·OH2 (IV), have been synthesized and characterized on the basis of elemental analysis, molar conductivity, 1H NMR, UV-vis, FT-IR and mass spectroscopy. All results confirm that the prepared compounds have 1:1 metal-to-ligand stoichiometry, octahedral configuration and the ligand behaves as a neutral tetradendate towards the metal ions. [CdL(OH2)2] (V), [CoL(OH2)2] (VI), [CuL(OH2)2] (VII) and [Ni(H2L)(NO3)2] (VIII) were synthesized pyrolytically in solid state from corresponding compounds (I-IV). Analytical results of complexes (V-VIII) show that the ligand behaves either as a neutral tetradendate or dianionic tetradentate ligand towards the metal ions. The binding of H2L and its copper complex (III) to DNA has been investigated by ultraviolet absorption spectroscopy. The experiments indicate that H2L and its copper complex (III) can bind to DNA through an intercalative mode. The H2L and its copper complex (III) exhibited anti-tumor activity against Ehrlich Acites Carcinoma (E.A.C) at the concentration of 100 μg/ml.