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New complexes of isonicotinoylhydrazone-9-anthraldehyde with Cu(II), Co(II) and Ni(II) have been prepared and characterized by analytical and physico-chemical techniques, such as elemental and thermal analyses, magnetic susceptibility and conductivity measurements, and electronic, EPR and IR spectral studies. The infrared spectral studies revealed the bidentate or monodentate nature of the Schiff base in the complexes; the pyridine nitrogen does not participate in the coordination. A tetrahedral geometry is suggested for the nitrate-complexes and an octahedral geometry for the others. Thermal studies support the chemical formulation of these complexes.

AbstractA polynuclear Cu(II) coordination system of {[Cu(ox)(NA)]. H2O}n (1), where ox = oxalate and NA = nicotinamide, and a mononuclear compound [Cu(NA)2(NO3)2(H2O)2] (2) were synthesized and characterized by single-crystal X-ray diffraction (1), IR, UV–VIS and EPR spectra, magnetic measurements and elemental analysis. In both complexes, Cu(II) adopts a distorted octahedral geometry. In 1 each copper center is coordinated to two oxalate units: one in a bis (bidentate) chelating mode linking two metal ions from the same plane, while the other, through a µ4 pattern, linking copper ions from adjacent positions. The sixth coordination position of each copper ion is occupied by the pyridinic nitrogen of a nicotinamide molecule. In 2 the Cu(II) basal plane consists of the oxygen atoms of the water molecules and the nitrogen atoms of nicotinamide molecules. The axial positions are occupied by oxygen atoms of the two nitrate groups, which are monodentate. The magnetic measurements for the polynuclear complex show antiferromagnetic coupling, the electronic structure modeling completing the insight to orbital factors of the spin interaction. [ABSTRACT FROM AUTHOR]

We report the evolution of structural, dielectric, ferroelectric and ferromagnetic properties in novel (Pb 1 − 3x/2 Nd x )(Ti 0.98 − y Fe y Mn 0.02 )O 3 perovskite ceramics(x = 0.08, 0 < y < 0.05). We found room-temperature ferroelectric polarization and ferromagnetism for higher amount of iron ions(y ≥ 0.04). The paraelectric-ferroelectric phase transition occurred between 650 and 670 K for 0 ≤ y ≤ 0.05. Ferromagnetic hysteresis was measured at different temperatures on samples with y ≥ 0.04. Detailed structural analysis evidenced the variation of unit cell parameters with y increasing, confirming the substitution of the iron element in the lattice. 57 Fe Mössbauer spectroscopy evidenced that iron ions occupy Ti positions in the perovskite lattice, with the oxidation state Fe 3 + and two coordination types. X-ray photoelectron spectroscopy confirmed the presence of iron only as Fe 3 + and, moreover, evidenced the presence of a substantial amount of Ti 3 + ions in the structure. The presence of both Fe 3 + (spin 5/2) in different coordinations as well as Ti 3 + (spin 1/2) magnetic ions in B-site positions drives the occurrence of magnetic properties from low temperature to above room temperature, through superexchange Fe 3 + -O-Fe 3 + , Fe 3 + -O-Ti 3 + and Ti 3 + -O-Ti 3 + interactions. The finding of coexistent ferroelectric and ferromagnetic properties in these compounds ground the route to facile synthesis of multiferroics by simply doping a classical perovskite ferroelectric material like PbTiO 3 with an adequate amount of transition magnetic ions. [ABSTRACT FROM AUTHOR]

We describe a simple approach to synthesize pure and manganese doped tin dioxide nanoparticles via a sol-gel method, starting from SnCl4 and MnCl2 in n-buthanol. The XRD analysis shows that well crystallized tetragonal SnO2 was obtained, with a crystallite size of 4nm, when samples were calcined at 350°C. Optical investigation shows that the manganese doping in SnO2 lattice leads to a decrease of the bang-gap energy due to the introduction of new unoccupied states by Mn 3d electrons. The SnO2 nanopowder exhibit strong blue-green luminescence, which indicate the presence of surface defects, such as oxygen vacancies. The emission intensity decreases as the dopant percent increases, indicating that manganese ions can block the blue-green emission by generating nonradiative decay channels or electron capture centres on the surface of nanocrystals. The magnetic susceptibility measurements show that the Mn ions are incorporated in the tin dioxide lattice, and that the samples are paramagnetic at room temperature. [ABSTRACT FROM AUTHOR]

In this study, three novel magnetic nanocomposites based on carboxyl-functionalized SBA-15 silica and magnetite nanoparticles were prepared through an effective and simple procedure and applied for methylene blue (MB) and malachite green G (MG) adsorption from single and binary solutions. Structure, composition, morphology, magnetic, and textural properties of the composites were thoroughly investigated. The influence of the amount of carboxyl functional groups on the physicochemical and adsorptive properties of the final materials was investigated. The capacity of the synthesized composites to adsorb MB and MG from single and binary solutions and the factors affecting the adsorption process, such as contact time, solution pH, and dye concentration, were assessed. Kinetic modelling showed that the dye adsorption mechanism followed the pseudo-second-order kinetic model, indicating that adsorption was a chemically controlled multilayer process. The adsorption rate was simultaneously controlled by external film diffusion and intraparticle diffusion. It was evidenced that the molecular geometry of the dye molecule plays a major role in the adsorption process, with the planar geometry of the MB molecule favoring adsorption. The analysis of equilibrium data revealed the best description of MB adsorption behavior by the Langmuir isotherm model, whereas the Freundlich model described better the MG adsorption.

As for the systematic investigations of magnetic behaviors and its related properties, computer simulations in extended quantum spin networks have been performed in good conditions via the generalized Ising model using the Monte Carlo-Metropolis algorithm with proven efficiencies. The present work, starting from a real magnetic system, provides detailed insights into the finite size effects and the ferrimagnetic properties in various 1 D, 2D and 3D geometries such as the magnetic moment, ordering temperature, and magnetocaloric effects with the different values of spins localized on the different coordinated sites.

Synthesis and biological activity investigation of complex compounds of Cu(II) are challenging issues because of the metal is not a xenobiotic one and the activity of ligands could be modulated by complexation. Complex combinations of Cu(II) and Pd(II) with thiosemicarbazone derivatives of 2-hydroxy-8-R-tricyclo[7.3.1.0.(2,7)]tridecane-13-one (where R=C(3)H(7), C(4)H(3)O) were synthesized. The characterization of the ligands and the newly formed compounds was done by (1)H NMR, (13)C NMR, UV-vis, IR, ESR spectroscopy, elemental analysis, molar electric conductibility and thermal studies. Experiments performed to identify the structures proved that the ligands coordinate to metal ions in different ways - neutral bidentate or mononegative bidentate. Also, if copper(II) acetate, copper(II) nitrate, copper(II) chloride and copper(II) thiocyanate were used, the ligands coordinated in a mononegative bidentate fashion. If copper(II) sulfate was used, the ligands coordinated in a neutral bidentate fashion. The biological activity for the copper(II) synthesized compounds was assessed in terms of antibacterial or antiproliferative activity. The antibacterial activity of the complexes against Staphylococcus aureus var. Oxford 6538, Escherichia coli ATCC 10536, Klebsielle pneumoniae ATCC 100131 and Candida albicans ATCC 10231 strains was studied and compared with that of free ligands. The effect of complex compounds on the proliferation of HeLa cells was tested. For all tested complexes an antiproliferative activity was noted at concentrations higher than 1 microM, but lower than 10 microM. Therefore, complex compounds of copper(II) were synthesized, structurally characterized and tested for biological activity, proving both antibacterial and antiproliferative activity., (Copyright (c) 2009. Published by Elsevier Masson SAS.)

Four novel polymeric coordination networks have been obtained through self-assembly processes involving alkoxo-bridged copperII species as nodes, and anionic cyano-complexes as linkers: infinity2[{Cu2(pa)2}{M(CN)2}2](M=Ag, 1; Au, 2), (infinity)3[{Cu4(mea)4}{Au(CN)2}4.H2O]3, and (infinity)3[{Cu2(pa)2}{Ni(CN)4}](pa = deprotonated propanolamine; mea = deprotonated monoethanolamine). The supramolecular architectures of compounds 1, and 2 are sustained by argentophilic or strong aurophilic interactions. The solid-state architectures of 1 and 2, which are isomorphous, consist of infinite layers, constructed from binuclear alkoxo-bridged nodes and [M(CN)2]- spacers. The layers are stacked in an offset parallel mode, and are further interconnected through Ag...Ag or Au...Au contacts (1: Ag...Ag 3.015 A; 2: Au....Au 3.069 A). Compound 3 consists of unique fourfold interpenetrating diamondoid nets. The diamondoid topology is built of heterocubane {Cu4O4} nodes, which are connected by [Au(CN)2]- rods. The Cu-O distances within the {Cu4O4} node vary between 1.927(2) and 2.679(1) A, showing unsymmetric bridging of the copper atoms. Aurophilic interactions are established between the bridging and terminal [Au(CN)2]- metalloligands, and connect the interpenetrating nets, resulting in infinite chains of gold atoms (the Au...Au distances vary between 3.253 and 3.305 [Angstrom]). Compound 4 exhibits a 3-D network constructed from {Cu2(pa)2]2+ nodes connected by square-planar [Ni(CN)4]2- ions. Compounds 1, 2 and 4 are weakly paramagnetic. The cryomagnetic investigation of reveals a gradual increase, followed by a decrease of the chiMT product, as the temperature is lowered. A superposition of ferro- (J1=+20.8 cm(-1)) and antiferromagnetic (J2=-6.4) interactions within the tetranuclear node was found. Antiferromagnetic interactions are established between the tetranuclear nodes (theta=-2.99 K).

The synthesis, structural determinations and magnetic properties of an original dinuclear Cu-Gd and two trinuclear Cu-Ln-Cu complexes (Ln = Gd or Dy) made with a Schiff base ligand and carboxylate ligands are reported. In each complex, the copper and gadolinium or dysprosium ions are linked by a double phenoxo bridge and a eta1:eta1:mu trifluoroacetato bridge. The dinuclear Cu-Gd complex exhibits the usual ferromagnetic interaction while the trinuclear (Cu-Gd-Cu) complexes can not be fitted with a simple Hamiltonian that only takes into account the Cu-Gd interaction. Introduction into the Hamiltonian of a Cu-Cu interaction between the terminal copper ions gives a nice fit in the case of a ferromagnetic Cu-Cu interaction (J'(Cu-Cu) = 8.3 and 9.8 cm(-1)). For the first time, the occurrence of a ferromagnetic interaction between the copper ions of the trinuclear entities is evidenced and supported by the field dependence of the magnetization. As there is no direct proof for the existence of an interaction between two centers through a third magnetic center located in between them, we can conclude that the existence of pi-pi stacking interactions through the phenyl rings of the ligands are responsible for the presence of these interactions.

A novel heterospin system, [(CuL)2Gd(TCNQ)2].TCNQ-.CH3OH.2CH3CN, is obtained by reacting the mononuclear complex, [CuL], with gadolinium(III) nitrate, followed by the substitution of the nitrato ions with anionic organic radicals.