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Abstract  

New solid complex of nitrilotriacetic acid and bismuth trichloride was synthesized by a solid phase reaction of nitrilotriacetic acid and bismuth trichloride at room temperature. The composition of the sample is BiCl3[N(CH2COOH)3]2.5. The crystal structure of the complex belongs to triclinic system with the lattice parameters: α=0.7849 nm, β=0.9821 nm, χ=2.0021 nm, α=96.50, β=98.76 and γ=90.49. The far-infrared spectra show the bonding between the Bi ion and N atom of nitrilotriacetic acid. The thermal analysis also demonstrates the complex formation between the bismuth ion and nitrilotriacetic acid. The gaseous pyrolysis product and the final residue in the thermal decomposition process are determined to check the thermal decomposition reaction.

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Abstract  

A new phase transition (III–IV) was found at 311 K in CsCoPO4 by DSC measurements. The crystal structure of all the phases, I–IV, in CsCoPO4 was studied by synchrotron-radiation X-ray powder diffraction. The diffractometry revealed that CsCoPO4 had the same crystal structure as that of corresponding phases in CsZnPO4. An extremely large particle size effect was found on III–IV phase transition in CsCoPO4; the phase transition enthalpy decreases with decreasing the particle size around 0.1 mm. Such large particle size effects had been also observed in CsZnPO4. However, no III–IV phase transition was observed in the particle smaller than 0.1 mm of CsZnPO4, while such a critical size was not found in CsCoPO4.

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Abstract  

Polypropylene (PP) /ethylene-octene copolymer (POE) blends with different content of POE were prepared by mixing chamber of a Haake torque rheometer. The crystallization behaviors and crystal structure of PP/POE blends were systematically investigated by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and polarized optical microscopy (POM). The results showed that PP spherulites became defective and the crystallization behavior was influenced intensely with the introduction of POE. At the low content of POE, the addition of POE decreases the apparent incubation period (Δt i) and the apparent total crystallization period (Δt c) of PP in blends due to the heterogeneous nucleation of POE, and small amount of β-form PP crystals form because of the existence of POE. However, at high content of POE, the addition of POE decreases the mobility of PP segments due to their strong intermolecular interaction and chain entanglements, resulting in retarding the crystallization of PP, decreasing in the amount of β-form PP crystals, and increasing in Δt i and Δt c of PP in blends.

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Thermal latent coordination compounds

The thermal degradation of imidazole and pyrazole adducts of metal acetates

Journal of Thermal Analysis and Calorimetry
Authors: M. Döring, W. Ludwig, and H. Görls

Abstract  

The thermal behaviour of complexes of the type M(HIm)2ac2 (HIm=imidazole,ac=acetate,M=Co, Ni, Cu) is different. Comparable to the thermal degradation of Ni(acac)2(HIm)2 [10] the Ni(HIm)2ac2 loss acetic acid by formation of Ni(Im)2. All nitrogen ligands are splitt off from the copper complex by formation of stable basic copper acetate. The cobalt compound eliminated acetic acid partially while acetate and imidazolate bridging species are obtained. The thermal behaviour of the acetate complexes of pyrazole and the bulky 3,5-dimethylpyrazole is quite similar. In a first step pyrazoliumacetate is removed. The crystal structure of Ni(HPz)4ac2 is determined by X-ray diffraction: monocline, space group C 2/c. The water molecule represents the centre of two N−H...O−H...O-bridges. The system of H-bridges in the compound relieves the proton transfer, indicated by the elimination of pyrazolium acetate.

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Abstract  

The complex of [Nd(BA)3bipy]2 (BA = benzoic acid; bipy = 2,2′-bipyridine) has been synthesized and characterized by elemental analysis, IR spectra, single crystal X-ray diffraction, and TG/DTG techniques. The crystal is monoclinic with space group P2(1)/n. The two–eight coordinated Nd3+ ions are linked together by four bridged BA ligands and each Nd3+ ion is further bonded to one chelated bidentate BA ligand and one 2,2′-bipyridine molecule. The thermal decomposition process of the title complex was discussed by TG/DTG and IR techniques. The non-isothermal kinetics was investigated by using double equal-double step method. The kinetic equation for the first stage can be expressed as dα/dt = A exp(−E/RT)(1 − α). The thermodynamic parameters (ΔH , ΔG , and ΔS ) and kinetic parameters (activation energy E and pre-exponential factor A) were also calculated.

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Abstract  

Bis-N,N′(salicylidene)-2,2′-dimethyl-1,3-propanediamine (LDMH2) has a high tendency to form polynuclear complexes. Two trinuclear complexes were obtained using this ligand and azide ions; (CuLDM)2 · Mn(N3)2 · (DMF)2, [(C19H20N2O2Cu)2 · Mn(N3)2 · (C3H7NO)2] and (CuLDM)2 · Cd(N3)2 · (DMF)2, [(C19H20N2O2Cu)2 · Cd(N3)2 · (C3H7NO)2]. The structures were identified with X-ray methods. TG and DSC methods were also employed to these complexes. Studies showed the (CuLDM)2 · Mn(N3)2 · (DMF)2 and (CuLDM)2 · Cd(N3)2 · (DMF)2 to be non-linear. Also μ-bridges were not encountered for the azide ions but were seen to form between the Cu and other metal via phenolic oxygens. Thermal analysis showed exothermic degradation of the azide ions destroying the trinuclear structure. Although azide containing structures show explosive characteristics, this was not observed for the present compounds.

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Abstract  

New complexes of the non-natural amino acid (p-iodo-phenylalanine) with divalent cobalt and nickel ions have been synthesized. The composition of the complexes is [M(IC6H4CH2CHNH2COO)2]2.5H2O (M=Co, Ni) and the crystal structure belongs to orthorhombic system. Infrared spectra indicate the nature of bonding in the complex. The first stage in the thermal decomposition process of the complex shows the presence of crystal water. The thermal decomposition process of cobalt complex differs from that of nickel. The intermediate and final residues in the thermal decomposition process have been analyzed to check the pyrolysis reactions. Thermal analysis indicates that the iodine atom of the ligand may coordinate to the metal ion in the lattice.

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Abstract  

The zinc(II) complex with nicotinamide (ncam) was prepared and investigated by single-crystal X-ray diffraction, infrared spectrum (FTIR), conductivity and thermal analysis techniques. The formula of complex is [Zn(ncam)2(H2O)4](NO3)2·2H2O. The nicotinamide molecule has three following donor sites: pyridine ring nitrogen, aminonitrogen and carbonyl group oxygen. In this monomeric complex, the Zn(II) ion is six-coordinated by two pyridine ring N atoms and four water O atoms in a slightly distorted octahedral arrangement. In the crystal structure, intermolecular O-H…O and N-H…O hydrogen bonds link the molecules to form a supramolecular structure. The complex is stable up to 323 and above 360 K it dehydrates in one step losing six water molecules. The dehydration proceeds in the range of 360–438 K, and its enthalpy value is equal to 62.6±1.5 kJ mol−1.

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Abstract  

The physicochemical properties (crystal structure, surface acidity, surface area, catalytic activity and electrical conductivity) of TiO2-silica gel mixed oxides have been investigated. A series of mixed oxides of various compositions in the range of 0–100% for each component were prepared by calcining the mixed oxides in air at temperatures of 115, 300, 600 and 1000°C. The results obtained have been discussed and correlated.

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