Ayman A. Abdel Aziz

Mononuclear Ru(II) Carbonyl Complexes Containing Quadridentate Schiff Bases as N2O2 Donors: Synthesis, Spectral, Catalytic Properties, and Antibacterial Activity

Reactions of Ru3(CO)12with novel tetradentate Schiff bases ligands H2L1−5 in benzene under reduced pressure afforded the formation of new Ru(II) complexes of the type [Ru(CO)2(L1−5)] where L = anion of N,N/bis(salicylaldehyde)4,5-dimethyl-1, 2-phenylenediamine (saldmophn), N,N/bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (saldcophn), N,N/bis(salicylalde-hyde)2,3-diaminonaphthalene (saldnap), N,N/bis(o-vanillin)4, 5-dimethy-l,2-phenylenediamine (ovaldmophn), and N,N/bis(o-vanillin)4,5-dichloro-1,2-phenylenediamine (ovaldcophn), respectively. All the newly synthesized complexes were investigated using elemental analysis, FT-IR, UV-Vis, mass spectrometry, and magnetic measurements. An octahedral structure has been tentatively proposed for the new complexes. All the new complexes have been found to be efficient catalysts for oxidation of primary and secondary alcohols into corresponding carbonyl compounds in presence of N-methylmorpholine-N-oxide (NMO) as the source of oxygen. In view of the biological activity, the ligands showed moderate bactericidal activities, where upon chelation with ruthenium, the bactericidal activities increased and the results have been compared with some known antibiotics.

Batch and hydrodynamic monitoring of vitamin C using novel periodate selective sensors based on a newly synthesized Ni(II)-Schiff bases complexes as a neutral receptors

A highly selective membrane electrodes based on a two newly synthesized nickel (II) Schiff bases, [NiL(1)] and [NiL(2)] where L(1) and L(2) are N,N/bis(salicylaldehyde)4,5-dimethyl-1,2-phenylenediamine (H(2)L(1)) and N,N/bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (H(2)L(2)) were used as a neutral carrier ionophores for static and hydrodynamic potentiometric mode of operations for the determination of periodate. Under static mode of operation, the sensors displayed a near-Nernstian slope of -66.1+/-0.8 and -59.9+/-1.1mV decade(-1) of activity and detection limits to 5.2x10(-6) and 7.3x10(-6)molL(-1) for the sensors based on [NiL(1)] and [NiL(2)], respectively. Under hydrodynamic mode of operation (FIA), the slope of the calibration plot, limit of detection, and working linear range were -71.1mV decade(-1) of activity, 7.3x10(-6) and 1.0x10(-5) to 1.0x10(-3)molL(-1), respectively. The response time of the sensors in whole concentration ranges was very short (<10s). The response of the sensors was independent on the pH range of 3-8. A tubular version was further developed and coupled to a flow injection system for ascorbic acid (AA) determination in beverages and pharmaceutical preparations. This approach was achieved by selecting a 50-cm reactor and an overall flow of 3mLmin(-1), and injecting volume 100microL of AA standards in a 1.0x10(-4)molL(-1) IO(4)(-) solution. Under these conditions, a linearity range of 2-13microgmL(-1), with a slope of 4.97mV (mg/L)(-1) (r(2)=0.9995), detection limit 0.9mgL(-1) and a reproducibility of +/-1.1mV (n=5) was recorded. This simple and inexpensive flow injection analysis manifold, with a good potentiometric detector, enabled the analysis of approximately 50 samples h(-1) without requiring pretreatment procedures. An average recovery of 98.8% and a mean standard deviation of 1.3% were obtained.

Synthesis, Spectral Characterization, SEM, Antimicrobial, Antioxidative Activity Evaluation, DNA Binding and DNA Cleavage Investigation of Transition Metal(II) Complexes Derived from a tetradentate Schiff base bearing thiophene moiety

A novel series of Co(II), Ni(II), Cu(II) and Zn(II) mononuclear complexes have been synthesized involving a potentially tetradentate Schiff base ligand, which was obtained by condensation of 2-aminophenol with 2,5-thiophene-dicarboxaldehyde. The complexes were synthesized via reflux reaction of methanolic solution of the appropriate Schiff base ligand with one equivalent of corresponding metal acetate salt. Based on different techniques including micro analysis, FT-IR, NMR, UV-Vis, ESR, ESI-mass and conductivity measurements, four-coordinated geometry was assigned for all complexes. Spectroscopic data have shown that, the reported Schiff base coordinated to metal ions as a dibasic tetradentate ligand through the phenolic oxygen and the azomethine nitrogen. The antimicrobial activities of the parent ligand and its complexes were investigated by using the agar disk diffusion method. Antioxidation properties of the novel complexes were investigated and it was found that all the complexes have good radical scavenging properties. The binding of complexes to calf thymus DNA (CT-DNA) was investigated by absorption, emission and viscosity measurements. Binding studies have shown that all the complexes interacted with CT-DNA via intercalation mode and the binding affinity varies with relative order as Cu(II) complex > Co(II) complex > Zn(II) complex > Ni(II) complex. Furthermore, DNA cleavage properties of the metal complexes were also investigated. The results suggested the possible utilization of novel complexes for pharmaceutical applications.

Microwave-Assisted Synthesis of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) Complexes of Tridentate Schiff Base N-(2-hydroxyphenyl) 2-hydroxy-5-bromobenzaldimine: Characterization, DNA Interaction, Antioxidant, and In Vitro Antimicrobial Studies

Five mononuclear complexes of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) with the Schiff base N-(2-hydroxyphenyl) 2-hydroxy-5-bromobenzaldimine were synthesized under microwave irradiation. The microwave irradiation method was found remarkably successful and gave higher yield at a less reaction time. The complexes were fully characterized by elemental analyses, FT-IR, 1H NMR, EPR, FAB mass spectra, electronic spectra, molar conductivity, magnetic susceptibility measurements, and thermogravimetric analyses (TGA). Structural compositions were assigned by mass spectral studies. Four-coordinate geometry has been assigned to these complexes tentatively. The interaction of the complexes with calf thymus DNA (CT-DNA) was investigated by absorption spectroscopy, emission spectroscopy, and viscosity measurements. The experimental evidences indicated that the binding strength follow the order Cu(II) > Mn(II) > Co(II) > Ni(II) >Zn (II). Moreover, the complexes were examined for their antioxidant activities against r...Five mononuclear complexes of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) with the Schiff base N-(2-hydroxyphenyl) 2-hydroxy-5-bromobenzaldimine were synthesized under microwave irradiation. The microwave irradiation method was found remarkably successful and gave higher yield at a less reaction time. The complexes were fully characterized by elemental analyses, FT-IR, 1H NMR, EPR, FAB mass spectra, electronic spectra, molar conductivity, magnetic susceptibility measurements, and thermogravimetric analyses (TGA). Structural compositions were assigned by mass spectral studies. Four-coordinate geometry has been assigned to these complexes tentatively. The interaction of the complexes with calf thymus DNA (CT-DNA) was investigated by absorption spectroscopy, emission spectroscopy, and viscosity measurements. The experimental evidences indicated that the binding strength follow the order Cu(II) > Mn(II) > Co(II) > Ni(II) >Zn (II). Moreover, the complexes were examined for their antioxidant activities against reactive oxygen species (O2 · − and HO · radicals). Additionally, the ligand and its complexes were screened in vitro for their antibacterial and antifungal activities. Preliminary information obtained from the present work would help in the development of nucleic acid molecular probes and new therapeutic reagents for diseases.

Spectroscopic, DFT, biological, DNA-binding and antioxidant studies of some metal chelates with a novel thiazole-derived Schiff base

Abstract Thermal reactions of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Ru(III) metal ions with a novel Schiff base ligand (HL) derived from the condensation of 2-aminothiazole and 2-hydroxy-1-naphthaldehyde resulted in the formation of a series of metal complexes, [Co(L)2(H2O)2]·2H2O (1), [Ni(L)(CH3COO)(H2O)2] (2), [Cu(L)2(H2O)2] (3), [Zn(L)2] (4), [Cd(L)(CH3COO)]·2H2O (5), and [Ru(L)2(H2O)2]Cl (6). The ligand and its complexes were characterized by means of elemental and thermal analyses, molar conductance, and magnetic moment measurements along with different spectroscopic techniques. The structure of the ligand was determined by X-ray crystal structure analysis and revealed that it crystallized in the orthorhombic space group P21cn with a Z value of 4. Theoretical calculations based on accurate DFT approximations were used to verify the structures of ligand and complexes. The relative reactivities were estimated using chemical descriptors analysis. The biological activities of the compounds were examined. The antioxidant activity against DPPH radical was evaluated in vitro by using spectrophotometric methods; the experiments showed potent antioxidant activity. Also, the interaction of the reported compounds with calf-thymus DNA (CT-DNA) by different techniques revealed that the complexes could bind to CT-DNA by intercalative mode. GRAPHICAL ABSTRACT