Mohamed H. Abdel-Rhman

Synthesis and structural investigation of mono- and polynuclear copper complexes of 4-ethyl-1-(pyridin-2-yl) thiosemicarbazide

The reaction between 2-hydrazinopyridine and ethylisothiocyanate produced 4-ethyl-1-(pyridin-2-yl) thiosemicarbazide (HEPTS). Its reaction with copper fluoride, chloride, bromide, acetate, nitrate, perchlorate, sulfate, carbonate, hydroxide and copper metal produced 15 Cu(II) complexes. The copper metal is easily oxidized in aqueous-ethanol solution of HEPTS giving [Cu2(EPTS)(H2O)3(OH)3]EtOH. Different complexes for the same anion were synthesized by controlling the heating time. Characterization by elemental, thermal, magnetic and spectral (electronic, IR, mass and ESR) studies showed the formation of mono-, di-, tri- and tetra nuclear complexes. The room temperature solid state ESR spectra of the complexes show an axial spectrum with dx2-y2 ground state, suggesting distorted tetragonal geometry around Cu(II) center. The kinetic and thermodynamic parameters for the different decomposition steps in the complexes were calculated. HEPTS and its Cu(II) complexes showed high activity against gram negative bacteria; [Cu3(EPTS)2(EtOH)2Br4] has more activity.

Laurene-type sesquiterpenes from the Red Sea red alga Laurencia obtusa as potential antitumor-antimicrobial agents.

Three new laurene-type sesquiterpenes, 12-hydroxy isolaurene (1), 8,11-dihydro-12-hydroxy isolaurene (2) and isolauraldehyde (3) were isolated from the organic extract of the red alga Laurencia obtusa. The chemical structures of isolates were determined by interpretation of their spectral data 1D and 2D NMR, UV, IR and MS. The newly isolated compounds were tested for their antimicrobial and antitumor activities. Compounds (1-3) exhibited potent activity against the gram-positive Bacillus subtilis and Staphylococcus aureus, where 3 proved to be the most active (MIC 35 and 27 μg/mL, respectively). Moreover, compound 3 exhibited a significant activity against Candida albicans (MIC of 70 μg/mL) and revealed to have very promising activity in an in vitro model of Ehrlich ascites Carcinoma.

Synthesis, spectral, thermal and biological studies on N(-)(2,4-dinitro-phenyl)-2-mercaptoacetohydrazide and its metal complexes.

Complexes of VO(2+), Cr(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+) and Hg(2+) ions with N(-)(2,4-dinitrophenyl)-2-mercaptoacetohydrazide (H2L) have been prepared and characterized on the basis of elemental analysis, molar conductance, thermal (TGA, DTGA), spectral (IR, NMR, UV-Visible, MS) and magnetic measurements. The IR spectra show that H2L behaves in a mononegative and/or binegative bidentate manner. The sulfate bridged the two complex molecules in [Cu(HL)(H2O)2(½SO4)]⋅3H2O. The acetate functions as a monodentate in [Ni(HL)(OAc)(H2O)3] and [Cr(HL)(OAc)2(H2O)(EtOH)]. Different stereochemistries are proposed: octahedral for Cr(III), Ni(II), Hg(II) and [Cu(HL)(H2O)2(SO4)0.5]⋅3H2O, square-based pyramid for [VO(HL)2]⋅EtOH, square-planar for [Co(L)(EtOH)(H2O)]⋅H2O, [Cu(L)(H2O)2] and tetrahedral for [Zn(L)(EtOH)(H2O)], [Cd(L)(EtOH)(H2O)] and [Cu2(HL)(H2O)6]Cl3⋅H2O according to the data of electronic spectra and magnetic measurements. The TGA data support the formula and indicate the outer and inner solvents as well as the final residue. The thermodynamic parameters are calculated using the Coats-Redfern and Horowitz-Metzger methods. H2L and [Zn(L)(EtOH)(H2O)] showed the highest cytotoxic activity while H2L has a higher antioxidant activity than ascorbic acid. The ionization constant of the ligand and the stability constant of the Cu(II)H2L in absence and presence of hexamine buffer were calculated.

Elaborated spectral analysis and modeling calculations on Co(II), Ni(II), Cu(II), Pd(II), Pt(II), and Pt(IV) nanoparticles complexes with simple thiourea derivative

A series of metal complexes was synthesized using a simple thiourea derivative. The prepared complexes were characterized using different techniques (FTIR, ESR, X-ray diffraction [XRD], TG/DTA, and TEM). The FTIR spectrum of the ligand shows the presence of its tautomer forms (keto–enol). The ligand coordinates as a neutral bidentate in the Pt(IV), Pd(II), and Pt(II) complexes. In the case of Co(II) and Ni(II) complexes, the ligand is mono-negative bidentate. The proposed complexes are four to six coordinate. The geometries are proposed based on electronic spectral data and magnetic measurements and were verified using other tools. The XRD patterns reflect the nanocrystalline structures except for the Cu(II) complex, which is amorphous. The TEM images for platinum complexes show nanosize particles and homogeneous metal ion distribution on the complex surface. The EPR spectrum of Cu(II) complex verified the octahedral geometry of the complex. Molecular modeling was performed to assign the structural formula proposed for the ligand based on the characterization results. Transmission electron micrographs of the Pt(IV) complex; inset shows the magnified image.

Synthesis and characterization of Hg(II) and Cd(II) complexes derived from the novel acenaphthaquinone-4-phenyl thiosemicarbazone and its CPE application

Abstract The new acenaphthaquinone-4-phenyl thiosemicarbazone (APTH) was synthesized. The reaction of Hg(II) and Cd(II) chloride with APTH yields bimetallic complexes, which are characterized by elemental, IR, UV-Vis., 1H-NMR and Mass spectroscopy. The APTH employed as a chelating agent for CPE procedure of trace amounts of mercury and cadmium from aqueous medium. The Hg(II) and Cd(II) is preconcentrated using 0.1% w/v Triton X-114 and 2 × 10−5 M APTH at pH 7. The calibration curve is linear in the ranges 0.25–3 and 0.25–7.5 ng/ml for Cd(II) and Hg(II), respectively. The proposed method was applied successfully in the determination of Hg(II) and Cd(II) in different water samples.

A new thiourea derivative [2-(3-ethylthioureido)benzoic acid] for cloud point extraction of some trace metals in water, biological and food samples

2-(3-Ethylthioureido)benzoic acid was prepared and characterized by electronic spectrum, elemental analysis, Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance spectrum and mass spectrum. The produced ligand was applied for the preconcentrative of Fe3+, Co2+, Cu2+ and Zn2+ in aqueous samples by cloud point extraction methodology. Triton X-114 was used as extractant. Experimental parameters that may affect the extraction process were examined and optimized; such as pH, ligand and triton concentrations, type of diluting solvent, extraction temperature and ionic strength. The calibration curves were linear upto 500μgL-1 for Fe3+, Cu2+ and Zn2+ and upto 200μgL-1 for Co2+. The achieved detection limits were 1.5, 0.23, 0.71 and 0.35μgL-1 for Fe3+, Co2+, Cu2+ and Zn2+ respectively. The accuracy was established by analysis of certified reference materials (Seronorm whole blood L2 and ZCS ZC85006 Tomato). The proposed procedure was used for preconcentration of these metal ions in water, biological and food samples prior to their determination by flame atomic absorption spectrometry.