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Water pollution by synthetic organic dyes is mainly regarded as environmental and ecological issues worldwide and requires feasible solutions in face of the short-term risk to human health and stability of eco-systems. Therefore, in this paper, the magnetic mesoporous composites (MMC) were synthesized by surfactant template sol–gel method, using cetyl-trimethylammonium bromide (CTAB) as mesoporous structure generator and investigated for anionic and cationic dyes removal from aqueous solutions. The magnetic iron oxide nanoparticles were obtained by reverse co-precipitation, followed by mesoporous silica coating through modified sol–gel method. The obtained materials were characterized by FT-IR spectroscopy, X-ray diffraction, transmission electron microscopy, Mossbauer spectroscopy, nitrogen adsorption, small-angle X-ray scattering and magnetization measurements. The influence of CTAB amount on the morpho-textural and structural properties of nanocomposites was studied. XRD and Mossbauer spectroscopy showed that the obtained nanocomposites were composed of pure maghemite nanoparticles, and TEM images revealed particles size around 10 nm, embedded in silica matrix. The combination of magnetic properties and high surface area values, up to 695 m2/g, made suitable the obtained nanocomposites to be used as adsorbents. The dye removal efficiency was higher than 90% after the first adsorption and remained above 65% after four adsorption–desorption cycles, indicating that the as-prepared magnetic mesoporous nanocomposites can be considered excellent adsorbent materials for the removal of both anionic and cationic dyes from wastewaters, and the recycling performance revealed the stability of MMC.

The heterometallic complexes [Cu(VO)2(CSN2H4)3Cl(OH)4]·H2O, [Cu2(VO)2(CSN2H4)2(C2H3O2)2·(OH)4], and [Cu2(VO)3(CSN2H4)4(C2H3O2)4(OH)4] were prepared and characterized in terms of their molecular electrical conductivity, electronic and IR spectra, and thermal behavior. A polymeric structure is proposed in which a thiourea ligand is bonded via a sulfur atom to the tetracoordinated copper(I) and via amino groups to the oxovanadium(IV) ion. The polymeric nature of the complexes is due to bridging via the OH, thiourea, and/or acetate moieties between oxovanadium(IV) coordination centers.

The thermal decomposition in air and in nitrogen atmosphere of binuclear complex compounds of Cu(II) and Co(II) containing the Mannich base N,N'-tetra(4-antipyrylmethyl)-1,2 diaminoethane (TAMEN) as a ligand, Cu 2 (TAMEN)Cl 4 and Co 2 (TAMEN)Cl 4 , were investigated. X-ray powder diffractometry, infrared spectroscopy and simultaneous thermogravimetry-differential thermal analysis (TG-DTA), have been used to characterize and to study the thermal behavior of these compounds. The results provided information concerning the stoichiometry, crystallinity, thermal stability and decomposition mechanism of the compounds.

The heterometallic complex [Cu(VO)2(C10H8N2)2(C2O4)3·2H2O] has been prepared and characterised by electronic and IR spectra, molecular electrical conductivity and thermal behaviour. A polymeric structure is proposed with oxalate and 4,4′-dipyridine acting as bridging ligands and VO(IV) of C4v symmetry and Cu(II) in octahedral surrounding the oxalate anion V4h.

Kinetics of thermal decomposition of three structurally similar complexes Co2Cu(C2O4)3 (R-diam)2, where R is ethyl, 1,2-propyl or 1,3-propyl, was studied under non-isothermal conditions and nitrogen dynamic atmosphere at heating rates of 5, 7, 10, 12 and 15 K min−1.

The thermal behaviour of the mixed-ligand complexes of cobalt(II) and copper(I) ions with antipyrine derivatives of 1,2-ethanediamine or piperazine (BAMP and TAMEN), with water and with 2-mercapto-benzothiazole (Hmbt) was investigated. The complexes contain 2-mercaptobenzothiazole (Hmbt, in the case of cobalt(II) ion) or dimercaptobenzothiazine (mbt–mbt, in the case of copper(I) ion) molecules as ligands and perchlorate (ClO4–) or thiocyanate (SCN – ) ion as counterion. By heating, water and ligands release the solid phase at lower temperature. At higher temperatures process of different organic reactions of ligands (e.g. polymerization, polycondensation) could be suggested to interpret the relative high final mass values.