Ioana Mindru

Iron, nickel and zinc malates coordination compounds cynthesis, characterization and thermal behaviour

The coordinations compounds (NH4)[Fe(C4H4O5)(OH)2]·0.5H2O, [Ni(C4H4O5)]·3H2O and [Zn(C4H4O5)]·5H2O were synthesized by a precipitation method and characterized by chemical analysis, spectral (IR, UV-VIS) and magnetical investigations. In the range 50-600°C stepped thermal decompositions occur with formation of anhydrous malates, malonates, oxoacetates (iron and nickel compounds) and hydroxocarbonate (Zn compound) as intermediates observed by FT-IR spectroscopy. α-Fe2O3, NiO and ZnO constitute the final decomposition products.

Thermal behaviour of some solid coordination compounds with malic acid as ligand

Abstract The authors present the results concerning the synthesis and the characterisation of some coordination compounds with malic acid as ligand: Co(C 4 H 4 O 5 )·2H 2 O, [Fe 2 (C 4 H 4 O 5 )(OH) 4 ]·4H 2 O and [Fe 2 Co(C 4 H 4 O 5 ) 2 (OH) 4 ]·6H 2 O. The heterometallic compound is a precursor of Co-ferrite. The values of the non-isothermal kinetic parameters for the dehydration reactions were determined. These values obtained by three integrals methods are in a satisfactory agreement.

Synthesis, Characterization and Thermal Decompositions Studies of Some Malates Coordination CompoundsI. iron nickel compounds

The thermal behaviour of three coordination compounds, potential precursors of nickel ferrite [Fe2Ni(C4H4O5)2.5(OH)2]NO3·5H2O,[Fe2Ni(C4H8O3N2)4](NO3)8·24H2O and (NH4)[Fe2Ni(C4H4O5)3(OH)3]·3H2O has been investigated to evaluate their suitability as precursors for nickel ferrite. For a complete and reliable assignment of the thermal transformations, the isolable solid intermediates and end products were characterized by IR, X-ray diffraction and Mössbauer investigations. A decomposition scheme is proposed.

Green Synthesis Methods of CoFe2O4 and Ag-CoFe2O4 Nanoparticles Using Hibiscus Extracts and Their Antimicrobial Potential

The cobalt ferrite CoFe2O4 and silver-cobalt ferrite Ag-CoFe2O4 nanoparticles were obtained through self-combustion and wet ferritization methods using aqueous extracts of Hibiscus rosa-sinensis flower and leaf. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and magnetic measurements were used for the characterization of the obtained oxide powders. The antimicrobial activity of the cobalt ferrite and silver-cobalt ferrite nanoparticles against Gram-positive and Gram-negative bacteria, as well as fungal strains, was investigated by qualitative and quantitative assays. The most active proved to be the Ag-CoFe2O4 nanoparticles, particularly those obtained through self-combustion using hibiscus leaf extract, which exhibited very low minimal inhibitory concentration values 0.031–0.062 mg/mL against all tested microbial strains, suggesting their potential for the development of novel antimicrobial agents.

Two Novel Copper coordination compounds with chiosulfate cnions as cigandsSolid state and reaction medium thermal decomposition

Thermal investigations of two novel coordination compounds, potential precursor of copper sulfides, namely [Cu2(S2O3)2(NH3)4]·5H2O and Na2[Cu4(S2O3)5(NH3)8]·2H2O were performed either in solid state (static air atmosphere), as well as in reaction medium. During both decompositions, Cu2+ reduction occurs. In solid state decomposition, a mixture containing sulfides and sulfates is observed. In the reaction medium, CuSy compounds with sulfur content y (0.66<y<1) dependent on thiosulfate concentration are obtained.

Synthesis of Y3Fe5O12 via Thermal Decomposition of Polynuclear Coordination Compounds

The possibility of obtaining yttrium iron garnet (Y3Fe5O12, YIG) through thermal decomposition of two coordination compounds with malate and gluconate anions as ligands, (NH4)6[Y3Fe5(C4O5H4)6(C4O5H3)6]·12H2O and (NH4)6[Y3Fe5(C6O7H10)6(C6O7H9)6]·8H2O. A mixture of simple oxides, namely Y2O3 and α-Fe2O3, orthorhombic ferrite YFeO3 and small amounts Y3Fe5O12, is generated from the thermolysis of malate compound, while a clean Y3Fe5O12 is obtained from gluconate compound.