Preparation and Characterization of Sulfadiazine Schiff Base Complexes of Co(II), Ni(II), Cu(II), and Mn(II)

Complexes of Co(II), Ni(II), Cu(II), and Mn(II) containing Schiff base NOS donor ligands have been synthesised via chemical and electrochemical techniques. The structure of the complexes has been elucidated by elemental analysis, conductance, magnetic susceptibility measurements, IR, ESR, electronic spectral studies and thermal techniques (TGA and DTA). The electrochemical behaviour of the metal complexes was studied using DC polarography and cyclic voltammetry. Antimicrobial activity of the title Schiff base and its complexes has been tested against different microorganisms.     

Synthesis and Properties of Mononuclear and Homobinuclear Chelates of Mn(II), Co(II), Ni(II), and Cu(II) with Phthalein Purple

Mono- and homobinuclear complexes of Mn(II), Co(II), Ni(II), and Cu(II) with phthalein purple are prepared and characterized by elemental analysis, thermal studies (TGA and DTA), spectral methods (IR, UV/Vis, and ESR), magnetic moment determination, and electrochemical reduction (DC polarography at DME and CV at HMDE). Thermal degradation of the complexes was studied by TGA and DTA where some thermodynamic parameters were determined. The mode of bonding and geometry of the complexes were determined from the spectral studies. Magnetic moment values showed some antiferromagnetism in the homobinuclear complexes. The reduction of the metal ions proceeds to the metallic state along an irreversible process.     

On real matrices with positive definite symmetric component

Inequalities concerning real square matrices A with positive definite symmetric component A+A^*are derived from certain inertia relations which hold for any complex (not necessarily real) square matrices A with positive definite

A+A^*     

Synthesis and characterization studies of 3-formyl chromone Schiff base complexes and their application as antitumor,antioxidant and antimicrobial

A novel Schiff base namely (E)-3-((2,6-dihydroxypyrimidin-4-ylimino)methyl)-4H-chromen-4-one and its Co (II), N (II)i, Cu (II) and Cd (II) complexes have been synthesized and proved by elemental analysis, molar conductance, thermal analysis (TGA), Inductive Coupled plasma (ICP), magnetic moment measurements, X-ray powder diffraction, IR, EI-mass,¹H NMR, ¹³C NMR,UV–Vis. and ESR spectral studies. On the basis of these data, it is evident that the Schiff base acts as bidentate via oxygen atom of carbonyl group and azomethine nitrogen atom for Co (II) complex; monobasic bidentate ligand for Ni (II), Cu (II) and Cd (II) complexes via oxygen atom of hydroxyl group and nitrogen atom of pyrimidine ring. The results showed all complexes have octahedral geometry. The average particle size of the ligand and its complexes were found to be 1.010–0.343 nm. The pharmacological action (antioxidant, antimicrobial and anticancer) of the prepared compounds is studied. The antitumor activity of the ligand and its metal complexes is evaluated against human liver carcinoma (HEPG2) cell. The data displayed the Co (II) complexes strong cytotoxicity where IC₅₀ values of Co (II) complex and 5-fluorouracil (stander drug) are 9.33 and 7.86 μg/ml respectively. The Co (II) and Cd (II) complexes have antibacterial activity more than ampicillin (stander drug). The interaction of the synthesized compounds with calf-thymus DNA (CT-DNA) has been performed via absorption spectra and viscosity technique. The DNA- binding constants have been determined.     

Spectral and thermal studies of 4-(1H-pyrazolo (3,4-d) pyrimidin-4-ylazo) benzene-1,3-diol complexes of cobalt(II), nickel(II) and copper(II)

4-(1H-Pyrazolo (3,4-d) pyrimidin-4-ylazo) benzene-1,3-diol was synthesized and characterized by various spectral and analytical techniques. Semiempirical quantum calculations using the AM1 method have been performed in order to evaluate the geometry and electronic structure of the title azodye in the ground state. The complex formation between Co(II), Ni(II) and Cu(II) ions and the title azodye was studied conductometrically and spectrophotometrically. The spectrophotometric determination of the title metal ions and titration using EDTA are reported. Co(II), Ni(II) and Cu(II) complexes of the title azodye have been synthesized and characterized by elemental analysis, conductivity, magnetic susceptibility, IR, UV-Vis and thermal analysis (TGA and DTA).The spectral and magnetic data suggested the octahedral geometry for Co(II) and Ni(II) complexes while Cu(II) complexes have square planar geometry. The thermal studies confirmed the chemical formulations of the title complexes. The thermal degradation takes place in two or three steps depending on the type of the metal and the geometry of the complexes. The kinetics of the decomposition was examined by using Coats-Redfern relation. The activation energies and other activation parameters (DeltaH, DeltaS and DeltaG) were computed and related to the bonding and stereochemistry of the complexes.     

New approach for evaluation optical absorption measurements of charge transfer complexes between dimethoxynaphthalenes and tetracyanoethylene: singular value decomposition method

Singular-value decomposition (SVD) method is a numerical multidimensional technique appropriate for evaluation of optical absorption measurements of 1:1 charge transfer complexes (CTCs). Matrix algebra of the absorption data for different solutions and wavenumbers is primarily used for evaluation of the equilibrium constant and to obtain some general expressions to illustrate physical significance of the results obtained. The influence of the ratio of the concentrations of donor and acceptor is examined. It can lead to information about the stoichiometry of the complex formed in solution. Calculations on data for CTCs between dimethoxynaphthalene (DMNs) and tetracyanoethylene (TCNE) in CH2Cl2 at various temperatures are described. The results suggest that there is a noticeable difference in the K4, caused by substitutions at alpha- and beta-positions, because the alpha-position of naphthalene exhibits relatively high electron density compared with the corresponding beta-position. There is a linear correlation between the donor HOMO energy and charge-transfer absorption maxima.     

Static laser light scattering (SLLS) investigations of the scattering parameters of a synthetic polymer

A laser light scattering system was built to study the scattering parameters of some materials in solution form. The light source used was an argon-ion laser at wavelength 488 nm (all lines). The investigated material was a synthetic polymer which has a wide range of applications in the field of teeth medicine applications. This is polymethyl-methacrylate (PMMA) which is used for the formation of artificial clamps. The PMMA was solved in both acetone and methyl-ethyl-ketone (MEK). The acetone solvent is chosen for its high specific refractive index increment dn/dc at the same wavelength 488 nm as the argon laser source. The angular distribution of the scattered laser light intensities of PMMA dissolved in acetone was measured at different scattering angles from 30 to 150° for each concentration. The angular distributions have a symmetrical behavior about the scattering angle π/2; by using the scattered intensities the Zimm plot was formed. The weight average molecular weight (WAMW) was determined, the two other scattering parameters like as radius of gyration, h, and the second verial coefficient, A₂ were determined.     

Mononuclear and Binuclear Fe(III), Co(II), Ni(II), and Cu(II) Complexes of 3,4′-Dihydroxyazobenzene-3′,4-dicarboxylic Acid and 3-Carboxy-4-hydroxyphenylazo-3-carboxy-4-hydroxynaphthalene

Summary. Fe(III), Co(II), Ni(II), and Cu(II) complexes of the title azodyes have been synthesized and characterized by elemental analysis, molar conductance, TGA, DTA, magnetic susceptibility measurements, IR, electronic and ESR spectral studies. The spectral studies suggest an octahedral geometry for Fe(III) and Co(II) complexes but a square planar geometry for Ni(II) and Cu(II) complexes. The kinetics of the catalysed oxidation of N,N,N,N-tetramethyl-p-phenylenediamine dihydrochloride (TMPPD) with mononuclear and binuclear copper complexes were studied to check the activity of these copper complexes in oxidizing organic amines. The electrochemical behaviour of the metal complexes was studied using DC polarography and cyclic voltammetry. Antimicrobial activity of the azo compounds and its complexes have been tested against different microorganisms.