Respective Metal Oxides Research Articles

Comparison of some properties of 2,3 - and 3,4 - dimethoxybenzoates of Cu(II), Co(II) and Nd(III)

The physicochemical properties of 2,4-, and 3,4- dimethoxybenzoates of Cu(II), Co(II) and Nd(III) were studied and compared to observe the -OCH3 substituent positions in benzene ring on the character of complexes. The analysed compounds are crystalline hydrated or anhydrous salts with colours depending on the kind of central ions: blue for Cu(II), pink for Co(II) and violet for Nd(III) complexes. The carboxylate groups bind as monodentate, bidentate bridging or chelating and even tridentate ligands. Their thermal stabilities were studied in air at 293-1173K. When heated the hydrated complexes release the water molecules and form anhydrous compounds which are then decomposed to the oxides of respective metals. Their magnetic moment values were determined in the range of 76-303K. The results reveal the compounds of Nd(III) and Co(II) to be the high-spin and that of Cu(II) forms dimer. The various positions of -OCH3 groups in benzene ring influence some of physicochemical properties of analysed compounds.

Solvent effects in the formation of hybrid materials based on titanium alkoxide-polysiloxane precursors

Hybrid TiO2-polysiloxane nanoparticles as well as hybrid TiO2-polysiloxane gels were prepared and characterized applying solvent-induced aggregation effects of titanium alkoxide-modified polysiloxane block copolymers. The functionalized polymers were prepared by the covalent attachment of coordination sites that allow the binding to metal alkoxides (M(OR)4; M = Ti; R = ethyl, butyl, isopropyl). Composition and structure of the hybrid polymers were investigated by NMR and FT-IR spectroscopy. In a second step the metal-alkoxide functionalities were hydrolyzed to form the respective metal oxides. Depending on the solvent in which the hydrolysis took place, hybrid nanoparticles or gels were obtained as a result of the different compatibility of the polysiloxane blocks towards the polarity of the solvents. The formed materials were investigated by NMR, FT-IR, atomic force microscopy (AFM), electron microscopy, and dynamic light scattering (DLS).

Complexes of 3,4-dimethoxybenzoic acid anion with Cu(II), Co(II), La(III), and Nd(III)

Physico-chemical properties of 3,4-dimethoxybenzoates of Co(II), Cu(II), La(III) and Nd(III)were studied. The complexes were obtained as hydrated or anhydrous polycrystalline solids with a metalion–ligand mole ratio of 1 : 2 for divalent ions and of 1 : 3 in the case of trivalent cations. Their coloursdepend on the kind of central ion: pink for Co(II) complex, blue for Cu(II), white for La(III) and violetfor Nd(III) complexes. The carboxylate groups in these compounds are monodentate, bidentate bridgingor chelating and tridentate ligands. Their thermal decomposition was studied in the range of 293–1173 K.Hydrated complexes lose crystallization water molecules in one step and form anhydrous compounds,that next decompose to the oxides of respective metals. 3,4 – Dimethoxybenzoates of Co(II) is directlydecomposed to the appropriate oxide and that of Nd(III) is also ultimately decomposed to its oxide butwith the intemediate formation of Nd 2 O 2 CO 3. . The magnetic moment values of 3,4–dimethoxybenzoatesdetermined in the range of 76–303 K change from 4.22 μ B to 4.61 μ B for Co(II) complex , from 0.49 μ Bto 1.17 μ B for Cu(II) complex , and from 2.69 μ B to 3.15 μ B for Nd(III) complex.

Magnetic, thermal and spectral characterization of 2,4-dimethoxybenzoates of Mn(II), Co(II) and Cu(II)

2,4 - Dimethoxybenzoates of Mn(II), Co(II) and Cu(II) have been synthesized as hydrated or anyhydrous polycrystalline solids and characterized by elemental analysis, IR spectroscopy, magnetic studies and X-ray diffraction measurements. They possess the following colours: Mn(II) – white, Co(II) – pink and Cu(II) – blue. The carboxylate groups bind as monodentate, or a symmetrical bidentate bridging ligands and tridentate. The thermal stabilities were determined in air at 293-1173K. When heated the hydratedcomplexes dehydrate to from anhydous salts which are decomposed to the oxides of respective metals. The magnetic susceptibilites of the 2,4-dimethoxybenzoates were measured over the range 76-303 K and their magnetic moments were calculated. The results reveal the complexes of Mn(II), Co(II) to be high-spin complexes and that of Cu(II) to form dimer.

Synthesis and characterization of bis(nicotinamide) m-hydroxybenzoate complexes of Co(II), Ni(II), Cu(II), and Zn(II)

Mixed-ligand m-hydroxybenzoate complexes of Co(II), Ni(II), Cu(II), and Zn(II) with nicotinamide were synthesized and characterized by elemental analysis, FT-IR spectrometry, solid state UV-vis spectrometry, and magnetic susceptibility measurements. The thermal behavior of the complexes was studied by simultaneous TG-DTA methods in static air atmosphere. The infrared spectral characteristics of the complexes are discussed and the mass spectra data are recorded. The complexes contain two water molecules, two m-hydroxybenzoato (m-hba), and two nicotinamide (na) ligands per formula unit. In these complexes, the m-hydroxybenzoate and nicotinamide behave as a monodentate ligand through acidic oxygen and nitrogen of the pyridine ring. The decomposition pathways and the stability of the complexes are interpreted in terms of the structural data. The final decomposition products were found to be the respective metal oxides.

Kinetics of thermal decomposition of mixed-ligand nikkel(II) and copper(II) complexes of 4-acyl pyrazolone derivative and pyridine

Thermal behaviors of two mixed-ligand complexes, [Ni(PMPP-SAL)(Py)3] and [Cu(PMPP-SAL)Py]·MeOH, (PMPP-SAL=1-phenyl-3-methyl-4-(salicylidene hydrazide)-propenylidene-pyrazolone-5, Py=pyridine), were studied by TG-DTG-DTA in dynamic air atmosphere. The complexes show the loss of pyridine molecule is followed by the decomposition of the PMPP-SAL anion and give respective metal oxides as residues. Meanwhile, the Ozawa-Flynn-Wall model-free analyses and multivariate non-linear regressions were applied to perform single and overall steps optimization. Kinetic parameters were given and the most probable mechanism functions were suggested in this study.

Syntheses and spectrothermal studies of triethanolamine complexes of Co(II), Ni(II), Cu(II) and Cd(II) squarates

The triethanolamine complexes, [M(tea)2]sq·nH2O, (n=2 for Co(II), n=0 for Ni(II), Cu(II) and n=1 for Cd(II), tea=triethanolamine, sq2−=squarate), have been synthesized and characterized by elemental analyses, magnetic susceptibility and conductivity measurements, UV-Vis and IR spectra, and thermal analyses techniques (TG, DTG and DTA). The Co(II), Ni(II) and Cu(II) complexes possess octahedral geometry, while the Cd(II) complex is monocapped trigonal prismatic geometry. Dianionic squarate behaves as a counter ion in the complexes. The thermal decomposition of these complexes takes place in three stages: (i) dehydration, (ii) release of the tea ligands and (iii) burning of organic residue. On the basis of the first DTGmax of the decomposition, the thermal stability of the anhydrous complexes follows the order: Ni(II), 289°C>Co(II), 230°C>Cu(II), 226°C>Cu(II), 170°C in static air atmosphere. The final decomposition products — the respective metal oxides — were identified by FTIR spectroscopy.

Synthesis and characterization of bis(N,N-diethylnicotinamide) m-hydroxybenzoate complexes of Co(II), Ni(H), Cu(II), and Zn(II)

Four novel mixed-ligand complexes of Co(II), Ni(II), Cu(II), and Zn(II) with m-hydroxybenzoate (m-Hba) and N,N-diethylnicotinamide (Dena) were synthesized and characterized on the basis of elemental analysis, FT-IR spectroscopic study, and solid state UV-Vis spectrophotometric and magnetic-susceptibility data. The thermal behavior of the complexes was studied by combined TG-DTA methods in static air atmosphere, and the mass spectra were recorded. The Co(II), Ni(II), and Zn(II) complexes, except for the Cu(II) complex, contain two molecules of coordinated water, two m-Hba, and two Dena ligands per formula unit. In these complexes, the m-Hba and Dena behave as monodentate ligands via acidic oxygen and nitrogen of the pyridine ring. In the Cu(II) complex, the m-Hba is coordinated as monoanionic bidentate ligand through acidic oxygen and carbonyl oxygen. Dena is bonded with Cu2+ as monodentate ligand by the nitrogen atom of the pyridine ring. The decomposition pathways and the stability of the complexes are interpreted in terms of the proposed structural data. The final decomposition products were found to be the respective metal oxides.

Complexes of 3,4-dimethoxybenzoic acid anion with Cu(II), Co(II), La(III), and Nd(III)

Physico-chemical properties of 3,4-dimethoxybenzoates of Co(II), Cu(II), La(III) and Nd(III) were studied. The complexes were obtained as hydrated or anhydrous polycrystalline solids with a metal ion-ligand mole ratio of 1 : 2 for divalent ions and of 1 : 3 in the case of trivalent cations. Their colours depend on the kind of central ion: pink for Co(II) complex, blue for Cu(II), white for La(III) and violet for Nd(III) complexes. The carboxylate groups in these compounds are monodentate, bidentate bridging or chelating and tridentate ligands. Their thermal decomposition was studied in the range of 293-1173 K. Hydrated complexes lose crystallization water molecules in one step and form anhydrous compounds, that next decompose to the oxides of respective metals. 3,4 - Dimethoxybenzoates of Co(II) is directly decomposed to the appropriate oxide and that of Nd(III) is also ultimately decomposed to its oxide but with the intemediate formation of Nd2O2CO3.. The magnetic moment values of 3,4-dimethoxybenzoates determined in the range of 76-303 K change from 4.22 µB to 4.61 µB for Co(II) complex , from 0.49 µB to 1.17 µB for Cu(II) complex , and from 2.69 µB to 3.15 µB for Nd(III) complex.

Spectral, thermal and X-ray studies on some new bis-hydrazine metal glyoxylates and bis-hydrazine mixed metal glyoxylates

Bis-hydrazine complexes of metal glyoxylates and mixed metal glyoxylates of 3d-metal ions of the formula M(OOCCHO) 2(N 2H 4) 2, where M = Mg, Mn, Co, Ni, Cu, Zn or Cd and M 1/3Co 2/3(OOCCHO) 2(N 2H 4) 2, where M = Mg, Mn, Ni, Zn or Cd, respectively, have been prepared and studied. The compositions of the complexes have been determined by chemical analyses. The magnetic moments and electronic spectra suggest a high-spin octahedral geometry for the metal complexes. Infrared spectral data indicate the bidentate bridging by hydrazine molecules and monodentate coordination by glyoxylate ions in both the metal and mixed metal compounds. Thermogravimetry and differential thermal analyses in air have been used to study the thermal behaviour of the complexes. The simultaneous TG-DTA traces of all the complexes show multi-step degradation and the final products are found to be the respective metal oxides in the case of metal complexes and metal cobaltites in the case of mixed metal complexes. The final residues were identified by their X-ray powder diffraction patterns. X-ray powder diffraction patterns of the complexes including mixed metal complexes are almost superimposable with in each of the series indicating isomorphism. The metal cobaltites MCo 2O 4, where M = Mg, Mn, Ni, Zn or Cd were also prepared by decomposing the respective mixed metal complex in a pre-heated silica crucible at about 300 °C, and their identities were confirmed by chemical analyses, infrared spectra and X-ray powder diffraction.

Cobalt(II), nickel(II) AND zinc(II) dicarboxylate complexes with hydrazine as bridged ligand

Abstract Cobalt, nickel and zinc dicarboxylate complexes containing neutral hydrazine as bridged bidentate ligand of the type MX(N2H4)n where n=1 for X=OOCCH2COO and n=2 for X=OOCCH2COO, OOCCH2CH2COO and OOCC(CH2)CH2COO have been prepared by aqueous reactions. These complexes have been characterized by analytical, spectral and thermal studies. The electronic spectra coupled with magnetic moments of cobalt and nickel complexes suggest these complexes are of high-spin variety with octahedral geometry. Infrared spectra indicate the bridging bidentate nature of hydrazine moieties present in both mono-hydrazine and bis-hydrazine complexes and the dicarboxylate ions coordinate to the metal as bidentate ligand through the monodentate coordination of each carboxylate ion. However, in the mono-hydrazine metal malonates both carboxylate ions act as bridged ligands. Simultaneous TG-DTA curves of all the complexes in air resulted in the formation of respective metal oxide as final residue at low temperatures (300–40...

Synthesis and Spectrothermal Studies of Thermochromic Diamine Complexes of Cobalt(III), Nickel(II) and Copper(II) Squarate. Crystal Structure of [Co(en)3](sq)1.5 · 6H2O

New adducts of ethylenediamine (en), N,N-dimethylethylenediamine (ndmen) and N,N′-dimethylethylenediamine (dmen) with squarate as counter-ions were synthesized and characterized by physico-chemical methods (IR and UV/vis spectroscopy, magnetic susceptibility and thermoanalytical measurements). The crystal structure of tris(ethylenediamine)cobalt(III) 1.5 squarate hexahydrate, [Co(en)3](sq)1.5 · 6H2O, was determined by single crystal X-ray diffraction. Co(III), Ni(II) and Cu(II) ions in the monomeric octahedral tris(ethylenediamine)cobalt(III) 1.5 squarate hexahydrate (1), tris(ethylenediamine)nickel(II) squarate 0.5 hydrate (2) and diaquabis(ethylenediamine)copper(II) squarate dihydrate (3) are chelated by ethylenediamines through two amine nitrogen atoms. Cu(II) atoms in the diaquabis(ndmen)copper(II) squarate (4) and diaquabis(dmen)copper(II) squarate (5) monomeric octahedral complexes are coordinated by ndmen and dmen molecules through two amine nitrogen atoms in a bidentate chelating manner. Water molecules complete the octahedral coordination. The orange (1), violet (4) and violet (5) complexes upon heating transform to claret, green and green species on dehydration, respectively, which revert immediately after cooling in the open atmosphere. The violet (3) complex upon heating loses water molecules yielding a deep blue dehydrated species, which on further heating undergoes an exothermic phase transition accompanied by thermochromism, deep blue to brown in the solid state. The decomposition mechanism and thermal stability of the solid complexes are interpreted in terms of their structures. The final decomposition products – the respective metal oxides – were identified by IR spectroscopy.

Divalent transition metal complexes of 3,5-pyrazoledicarboxylate

New divalent transition metal 3,5-pyrazoledicarboxylate hydrates of empirical formula Mpz(COO)2(H2O)2, where M=Mn, Co, Ni, Cu, Zn and Cd (pz(COO)2=3,5-pyrazoledicarboxylate), metal hydrazine complexes of the type Mpz(COO)2N2H4 where M=Co, Zn or Cd and Mpz(COO)2nN2H4·H2O, where n=1 for M=Ni and n=0.5 for M=Cu have been prepared and characterized by physico-chemical methods. Electronic spectroscopic data suggest that Co and Ni complexes adopt an octahedral geometry. The IR spectra confirm the presence of unidentate carboxylate anion (Δν=νasy(COO–)–νsym(COO–)>215 cm–1) in all the complexes and bidentate bridging hydrazine (νN–N=985–950 cm–1) in the metal hydrazine complexes. Both metal carboxylate and metal hydrazine carboxylate complexes undergo endothermic dehydration and/or dehydrazination followed by exothermic decomposition of organic moiety to give the respective metal oxides as the end products except manganese pyrazoledicarboxylate hydrate, which leaves manganese carbonate. X-ray powder diffraction patterns reveal that the metal carboxylate hydrates are isomorphous as are those of metal hydrazine complexes of cobalt, zinc and cadmium.

A comparative study on the thermal decomposition of some transition metal carboxylates

Thermal decomposition of transition metal malonates, MCH2C2O4⋅xH2O and transition metal succinates, M(CH2)2C2O4⋅xH2O (M=Mn, Fe, Co, Ni, Cu, Zn) has been studied employing TG, DTG, DTA, XRD, SEM, IR and Mossbauer spectroscopic techniques. After dehydration, the anhydrous metal malonates and succinates decompose directly to their respective metal oxides in the temperature ranges 310–400 and 400–525°C, respectively. The oxides obtained have been found to be nanosized. The thermal stability of succinates have been found to be higher than that of the respective malonates.

Thermal, spectral and magnetic properties of 3,5-dimethoxybenzoates of Co(II), Ni(II) and Cu(II)

The complexes of 3,5-dimethoxybenzoates of Co(II), Ni(II) and Cu(II) have been synthesized as hydrated polycrystalline solids and characterized by elemental analysis, IR, FIR and electronic spectroscopy, magnetic studies and X-ray diffraction measurements. They possess colours typical of the M(II) ions: Cu-blue, Ni-green, Co-pink. The carboxylate groups bind as monodentate or a symmetrical, bidentate chelating or bridging ligands. The thermal stabilities were determined in air. When heated they dehydrate to form anhydrous salts which are decomposed to the oxides of respective metals. The magnetic susceptibilities of the complexes were measured over the range 77-300 K and the magnetic moments were calculated. The results reveal the complexes of Ni(II) and Co(II) to be high-spin complexes and that of Cu(II) to form dimer.

Review of development of a silica-based thermoluminescence dosimeter

Development of a silica-based material suitable for thermoluminescence dosimetry (TLD) is described. Doped silica samples were prepared in-house using the sol–gel technique. Results from a micro-X-ray fluorescence (μ-XRF) study of Zn-doped silica have confirmed the capability of the sol–gel processing steps in producing homogeneously doped samples. The ability of sol–gel processing in producing doped samples with different dopant charge states has been illustrated in the case of copper (I)- and copper (II)-doped silica samples. The charge states of the dopants have been verified using the technique of X-ray absorption near-edge structure (XANES). X-ray diffraction (XRD) investigations have shown the structure of samples doped with erbium, copper (I) and copper (II) (listed in order of decreasing effect) to be altered by the dopants, albeit with the samples remaining in an amorphous state. Local structure studies, carried out using the method of extended X-ray absorption fine structure (EXAFS), reveal that in most cases the local environment of the dopant is similar to the respective native structure of the respective metal oxides. Conversely, in a number of cases, the dopant atoms occupy the silicon sites in the silica tetragonal geometry. Thermoluminescence (TL) studies were carried out on aluminium, copper (I), germanium, manganese, tin, and zinc-doped silica samples. Weight for weight, the most sensitive thermoluminescent material was found to be 4.0 mol% aluminium-doped silica, providing ∼3.5 times the TL yield of TLD100 and ∼5.4 times that of germanium-doped silica. The photon dose response of aluminium-doped silica was observed to be linear over the range of investigated dose, 0.5–10.0 Gy.

Thermoanalytical and spectral properties of new rare-earth metal 2-pyrazinecarboxylate hydrates

New 4f-trivalent lanthanide 2-pyrazinecarboxylate hydrates of composition Ln(pyzCOO) 3 ·3.5H 2 O, where Ln =La, Ce, Pr, Nd, Sm and Dy have been isolated from aqueous solution containing the respective metal nitrates and 2-pyrazinecarboxylic acid (HpyzCOO), in 1:3 molar ratios. The complexes have been characterized by analytical, electronic and IR spectroscopic, thermal analysis and X-ray diffraction studies. The OCO - group of 2-pyrazinecarboxylate bridges in both mono and bidentate fashion (n as(COO) =1612 and 1578 cm -1 ; n s(COO) =1423 and 1388 cm -1 ) as evidenced by IR data. The IR spectra further indicate that coordination takes place through the carboxyl group and the nearest hetero-ring nitrogen atom. The bonding parameters b, b 1/2 , pd and e have been calculated from the electronic spectral (hypersensitive) bands of Pr(III) and Nd(III) complexes. Both IR and thermal data reveal the presence of a coordinated water and two and a half lattice water molecules in the complexes. It is further substantiated by single crystal X-ray study for the corresponding lanthanum compound. Based on the results obtained, nine coordination is proposed for the lanthanide ions. Simultaneous TG-DTA of the complexes show that they are thermally stable up to 150°C and undergo endothermic (~155 and 250°C) followed by exothermic (~480°C) decompositions to give the respective metal oxides as the final product. The compounds are found to be isostructural as evidenced from X-ray powder patterns.

XPS study of the ultrathin a-C:H films deposited onto ion beam nitrided AISI 316 steel

Effects of the steel surface treatment by nitrogen ion beam and subsequent deposition of the diamond-like carbon (hydrogenated amorphous carbon (a-C:H) and nitrogen doped hydrogenated amorphous carbon (a-CN x :H)) films were investigated by means of the X-ray photoelectron spectroscopy (XPS). Experimental results show that nitrogen ion beam treatment of the AISI 316 steel surface even at room temperature results in the formation of the Cr and Fe nitrides. Replacement of the respective metal oxides by the nitrides takes place. Formation of the C N bonds was observed for both ultrathin a-C:H and ultrathin a-CN x :H layers deposited onto the nitrided steel. Some Fe and/or Cr nitrides still were presented at the interface after the film deposition, too. Increased adhesion between the steel substrate and hydrogenated amorphous carbon layer after the ion beam nitridation was explained by three main factors. The first two is steel surface deoxidisation/passivation by nitrogen as a result of the ion beam treatment. The third one is carbon nitride formation at the nitrided steel–hydrogenated amorphous carbon (or a-CN x :H) film interface.

Thermal kinetic TG-analysis of the mixed-ligand copper(II) and nickel(II) complexes of N-(1-phenyl-3-methyl-4-benzylidene-5-pyrazolone) p-nitrobezoylhydrazide and pyridine

Thermal behaviors of three mixed-ligand complexes, [Ni(PMBP-PNH)(Py) 3], [Ni(PMBP-PNH)Py] and [Cu(PMBP-PNH)Py] (PMBP-PNH = N-(1-phenyl-3-methyl-4-benzylidene-5-pyrazolone) p-nitrobezoylhydrazide; Py = pyridine), were studied by TG and DTG in dynamic air atmosphere. The complexes show the loss of pyridine molecule which is followed by the decomposition of the PMBP-PNH anion and give respective metal oxides as residues. Meanwhile, the Ozawa-Flynn-Wall model-free analyses and multivariate non-linear regression were applied to perform single and overall steps optimization. Kinetic parameters were given and the most probable mechanism functions were suggested in this study.

Structure and optical properties of (Al2O3)x(Tio)1−x thin films prepared by a sol–gel processing

(Al2O3)x(TiO2)1−x thin films obtained from sol solutions by spin coating technique have been studied. The chemical composition and stoichiometry of the films have been determined by X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectroscopy (RBS). The peaks at 461.48eV for Al2p and Ti2p at 74.4eV are characteristic for the respective metal oxides and indicate the presence of Al2O3 and TiO2. The refractive index, dielectric constant and optical band gap for direct transitions have been determined for varying Al:Ti ratios in the starting solution.