共查询到20条相似文献,搜索用时 31 毫秒
1.
Saud M. A. Katib 《Journal of Thermal Analysis and Calorimetry》2011,103(2):647-652
Thermal decomposition of Ni(II), Pd(II), and Pt(II) complexes of N-pyrimidin-2ylthiourea (AllPmTu) have been studied by TG, DTG, and DTA and by electron impact (EI) mass spectra. The complexes
have the molecular formulae as [Ni(AllPmTu)Cl2(H2O)], [Ni(AllPmTu)2Cl2(H2O)2], and [M(AllPmTu)Cl2], where M = PdII or PtII, and [Pt(AllPmTu)2]. The TG curves show that Ni(II) complexes decompose in three stages to yield NiO as a residue, while Pd(II) and Pt(II) decompose
in two stages to yield MS residues. The initial mass losses correspond to elimination of allylamine for Pd(II) and Pt(II)
complexes but, allyisothiocyanate for both Ni(II) complexes revealing that sulfur atom of thiourea part is involved in coordination
to Pd(II) and Pt(II) but does not to Ni(II). Kinetic parameters (E
#, n, ΔH
#, ΔS
#, ΔG
#) of the decomposition stages are determined and correlated with bonding and structural properties of the complexes. The EI
mass spectra of the complexes show fragments corresponding to the evolved and intermediate species. 相似文献
2.
Nopsiri Chaiyo Rangson Muanghlua Surasak Niemcharoen Banjong Boonchom Panpailin Seeharaj Naratip Vittayakorn 《Journal of Thermal Analysis and Calorimetry》2012,107(3):1023-1029
The thermal transformation of Na2C2O4 was studied in N2 atmosphere using thermo gravimetric (TG) analysis and differential thermal analysis (DTA). Na2C2O4 and its decomposed product were characterized using a scanning electron microscope (SEM) and the X-ray diffraction technique
(XRD). The non-isothermal kinetic of the decomposition was studied by the mean of Ozawa and Kissinger–Akahira–Sunose (KAS)
methods. The activation energies (E
α) of Na2C2O4 decomposition were found to be consistent. Decreasing E
α at increased decomposition temperature indicated the multi-step nature of the process. The possible conversion function estimated
through the Liqing–Donghua method was ‘cylindrical symmetry (R2 or F1/2)’ of the phase boundary mechanism. Thermodynamic functions (ΔH*, ΔG* and ΔS*), calculated by the Activated complex theory and kinetic parameters, indicated that the decomposition step is a high energy
pathway and revealed a very hard mechanism. 相似文献
3.
Lanthanum(III) tris-tartrato lanthanate(III) decahydrate, La[La(C4H4O6)3]·10H2O has been synthesized and characterized by elemental analysis, IR, electronic spectral and X-ray powder diffraction studies.
Thermal studies (TG, DTG and DTA) in air showed a complex decomposition pattern with the generation of an anhydrous species
at ~170°C. The end product was found to be mainly a mixture of La2O3 and carbides at ~970°C through the formation of several intermediates at different temperature. The residual product in DSC
study in nitrogen at 670°C is assumed to be a similar mixture generated at 500°C in TG in air. Kinetic parameters, such as,
E*, ΔH, ΔS, etc. obtained from DSC are discussed. IR and X-ray powder diffraction studies identified some of the decomposition products.
The tentative mechanism for the thermal decomposition in air of the compound is proposed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
《Journal of Coordination Chemistry》2012,65(12):1935-1950
The complexes of alloxan with Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) Cd(II), Hg(II), Ti(IV) and Zr(II) have been isolated and characterized on the basis of elemental analysis, molar conductivity, spectral studies (mid infrared, 1H-NMR and UV/vis spectra), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The thermal decomposition of the metal complexes was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The kinetic thermodynamic parameters, E*, ΔH*, ΔS* and ΔG*, were calculated using Coats and Redfern and Horowitz and Metzger equations. The ligand and its complexes have been studied for possible biological activity including antibacterial and antifungal activity. 相似文献
5.
Banjong Boonchom 《Journal of Thermal Analysis and Calorimetry》2009,98(3):863-871
The thermal decomposition of magnesium hydrogen phosphate trihydrate MgHPO4 · 3H2O was investigated in air atmosphere using TG-DTG-DTA. MgHPO4 · 3H2O decomposes in a single step and its final decomposition product (Mg2P2O7) was obtained. The activation energies of the decomposition step of MgHPO4 · 3H2O were calculated through the isoconversional methods of the Ozawa, Kissinger–Akahira–Sunose (KAS) and Iterative equation,
and the possible conversion function has been estimated through the Coats and Redfern integral equation. The activation energies
calculated for the decomposition reaction by different techniques and methods were found to be consistent. The better kinetic
model of the decomposition reaction for MgHPO4 · 3H2O is the F
1/3 model as a simple n-order reaction of “chemical process or mechanism no-invoking equation”. The thermodynamic functions (ΔH*, ΔG* and ΔS*) of the decomposition reaction are calculated by the activated complex theory and indicate that the process is non-spontaneous
without connecting with the introduction of heat. 相似文献
6.
K. Lutfar Rahman M. A. Mamun M. Q. Ehsan 《Russian Journal of Inorganic Chemistry》2011,56(9):1436-1442
Metal complexes of Niacin (3-pyridin carboxylic acid) were prepared in aqueous medium and characterized by different physico-chemical
methods. On the basis of elemental analysis the empirical formula of the complexes have been proposed as [Fe(C6H4NO2)]Cl2, [Co(C6H4NO2)]Cl, [Zn(C6H4NO2)]Cl, [Cd(C6H4NO2)]Cl and [Hg(C6H4NO2)]Cl. IR spectral data indicate that the metal-ligand bonding occurs through nitrogen atom of aromatic ring and oxygen atom
of COO−-group. UV-visible spectra show that Fe(III) and Co(II) complexes show d-d electronic transition in addition to π → π*, n → π* and n → σ* transitions. The Fe(II) and Co(II) complexes are paramagnetic. QSTG analysis data strongly support the absence of water
molecules in the complexes, and the weight of the residue corresponds to the respective metal oxides. Cyclic voltammetric
studies suggest that the redox properties of Zn(II), Cd(II) and Hg(II) in their complexes are modified compared to the uncoordinated
metal ion. The CV data also indicate that the charge transfer processes are not reversible. 相似文献
7.
A 56.56-kDa extracellular chitinase from Paenibacillus sp. D1 was purified to 52.3-fold by ion exchange chromatography using SP Sepharose. Maximum enzyme activity was recorded
at pH 5.0 and 50 °C. MALDI-LC-MS/MS analysis identified the purified enzyme as chitinase with 60% similarity to chitinase
Chi55 of Paenibacillus ehimensis. The activation energy (E
a) for chitin hydrolysis and temperature quotient (Q
10) at optimum temperature was found to be 19.14 kJ/mol and 1.25, respectively. Determination of kinetic constants k
m, V
max, k
cat, and k
cat/k
m and thermodynamic parameters ΔH*, ΔS*, ΔG*, ΔG*E–S, and ΔG*E–T revealed high affinity of the enzyme for chitin. The enzyme exhibited higher stability in presence of commonly used protectant
fungicides Captan, Carbendazim, and Mancozeb compared to control as reflected from the t
1/2 values suggesting its applicability in integrated pest management for control of soil-borne fungal phytopathogens. The order
of stability of chitinase in presence of fungicides at 80 °C as revealed from t
1/2 values and thermodynamic parameters E
a(d) (activation energy for irreversible deactivation), ΔH*, ΔG*, and ΔS* was: Captan > Carbendazim > Mancozeb > control. The present study is the first report on thermodynamic and kinetic characterization
of chitinase from Paenibacillus sp. D1. 相似文献
8.
Moamen S. Refat 《Journal of Thermal Analysis and Calorimetry》2010,102(3):1095-1103
Three Mn(II), Co(II), and Cu(II) new transition metal complexes of the fluorescence dye: 2-(2′-hydroxy-5′-phenyl)-5-aminobenzotriazole/PBT
derived from o-aminophenol and m-phenylenediamine have been synthesized. The structural interpretations were confirmed from elemental analyses, magnetic susceptibility
and molar conductivity, as well as from mass, IR, UV–Vis spectral studies. From the analytical, spectroscopic, and thermal
data, the stoichiometry of the mentioned complexes was found to be 1:2 (metal:ligand). The molar conductance data revealed
that all the metal chelates are non-electrolytes and the chloride ions exist inside the coordination sphere. The thermal stabilities
of these complexes were studied by thermogravimetric (TG/DTG) and the decomposition steps of these three complexes are investigated.
The kinetic parameters such as the energy of activation (E*), pre-exponential factor (A), activation entropy (ΔS*), activation enthalpy (ΔH*), and free energy of activation (ΔG*) have been reported. Photostability of phenyl benzotriazole as fluorescence dye and their metal complexes doped in polymethyl
methacrylate/PMMA were exposed to UV–Vis radiation and the change in the absorption spectra was achieved at different times
during irradiation period. 相似文献
9.
The thermal decomposition of some Ni(II)-carboxylate-imidazole complexes in a nitrogen atmosphere was studied non-isothermally.
From the non-isothermal thermoanalytical data, it was found that these complexes decompose through a stepwise release of imidazole
molecules and/or CO ones forming unstable intermediates which produce metal oxide or the metal as a final decomposition product.
TG in conjunction with DTG were used to evaluate the kinetic and thermodynamic parameters of the decomposition reaction. The
kinetic studies were performed employing a computer-oriented kinetic analysis of each set of W-T data obtained under constant heating rate. The diffusion processes are the decisive mechanisms for the decomposition. The
values of ΔE, A, ΔH, ΔS and ΔG for activation were calculated for the complexes and correlated to variation in their structure.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
I. M. M. Kenawy M. A. H. Hafez R. R. Lashein 《Journal of Thermal Analysis and Calorimetry》2001,65(3):723-736
The complexes formed by the chemically modified chloromethylated poly(styrene)-PAN (CMPS-PAN) as a resin chelating ion exchanger
were characterized by infrared and potentiometry. The thermal degradation of pure CMPS-PAN resin and its complexes with Au3+, Cr3+, Cu2+, Fe3+, Mn2+ and Pt4+ in air atmosphere has been studied using thermal gravimetry (TG) and derivative thermal gravimetry (DTG). The results showed
that four different steps accompany the decomposition of CMPS-PAN resin and its complexes with the metal ions. These stages
were affected by the presence of the investigated metal ions. The thermal degradation of CMPS-PAN resin in the presence of
the ions showed different stability of the resin in the following decreasing order: Au3+>Pt4+>Mn2+>Cu2+>Cr3+>Fe3+. On the basis of the applicability of a non-isothermal kinetic equation, the decomposition process was a first-order reaction.
The activation energy, Ea, the entropy change, ΔS
*, the enthalpy change, ΔH
* and the Gibbs free energy of activation, ΔG
* were calculated by applying the theory of the reaction rates. The effect of the different central metal ions on the calculated
thermodynamic activation parameters was discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
Refat MS Mohamed SF 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,82(1):108-117
The complexes of sulfasalazine (H3Suz) with some of alkaline metals Mg(II), Ca(II), Sr(II) and Ba(II) have been investigated. Sulfasalazine complexes were synthesized and characterized by spectroscopic tools; infrared spectra, electronic and mass spectra. The IR spectra of the prepared complexes were suggested that the H3Suz behaves as a bi-dentate ligand through the carboxylic and phenolic groups. The molar conductance measurements gave an idea about the non-electrolytic behavior of the H3Suz complexes. The thermal decomposition processes for metal(II) complexes of H3Suz viz: [M(HSuz)(H2O)4] (where M = Mg(II), Ca(II), Sr(II) or Ba(II)) have been accomplished on the basis of TG/DTG and DTA studies, and the formula conforms to the stoichiometry of the complexes based on elemental analysis. The kinetic analyses of the thermal decomposition were studied using the Coats–Redfern and Horowitz–Metzger equations. The antitumor and antimicrobial activities of the H3Suz and their alkaline metal(II) complexes were evaluated. 相似文献
12.
Shashi B. Kalia Priyanka Sankhyan R. Puri J. Christopher 《Journal of Thermal Analysis and Calorimetry》2012,107(2):597-605
Non-isothermal techniques, i.e. thermogravimetry (TG) and differential scanning calorimetry (DSC), have been applied to investigate
the thermal behaviour of carbaryl (1-naphthyl-N-methylcarbamate = 1-Naph-N-Mecbm) and its complexes, M(1-Naph-N-Mecbm)4X2, where M = Cu, X = Cl, NO3 and CH3COO and M = Zn, X = Cl. Carbaryl and Zn(1-Naph-N-Mecbm)4Cl2 complex exhibit two-stage thermal decomposition while the copper(II) complexes exhibit three and four-stage decomposition
in their TG curves. The nature of the metal ion has been found to play highly influential role on the nature of thermal decomposition
products as well as energy of activation ‘E*’. The presence of different anions does not seem to alter the thermal decomposition patterns. The complexes display weak
to medium intensity exothermic and endothermic DSC curves, while the free ligand exhibits two endothermic peaks. The kinetic
and thermodynamic parameters namely, the energy of activation ‘E*’, the frequency factor ‘A’ and the entropy of activation ‘S*’ etc. have been rationalized in relation to the bonding aspect of the carbaryl ligand. The nature and chemical composition
of the residues of the decomposition steps have been studied by elemental analysis and FTIR data. 相似文献
13.
W. Ferenc A. Dziewulska-Kułaczkowska J. Sarzyński B. Paszkowska 《Journal of Thermal Analysis and Calorimetry》2008,91(1):285-292
4-Chloro-2-methoxybenzoates of heavy lanthanides(III) and yttrium(III) were obtained as mono-, di-, tri-or tetrahydrates with
metal to ligand ratio of 1:3 and general formula Ln(C8H6ClO3)3·nH2O, where n=1 for Ln=Er, n=2 for Ln=Tb, Dy, Tm, Y, n=3 for Ln=Ho and n=4 for Yb and Lu. The complexes were characterized by elemental analysis, FTIR spectra, TG, DTA and DSC curves, X-ray diffraction
and magnetic measurements.
The carboxylate group appears to be a symmetrical bidentate chelating ligand. All complexes are polycrystalline compounds.
The values of enthalpy, ΔH, of the dehydration process for analysed complexes were also determined. The solubilities of heavy lanthanide(III) 4-chloro-2-methoxybenzoates
in water at 293 K are of the order of 10−4 mol dm−3. The magnetic moments were determined over the range of 76–303 K. The results indicate that there is no influence of the
ligand field of 4f electrons on lanthanide ions and the metal ligand bonding is mainly electrostatic in nature. 相似文献
14.
The TG and DTA of a new series of Mn(II) and Cu(II) complexes with a number of newly prepared bisazo-dianil ligands were studied
in the temperature range (20-700°C). The TG and DTG curves display to main steps, the first one within the temperature range
(25-330°C) correspond to the elimination of water or and ethanol from the complexes. The second step within the range (350-625°C)
is due to the decomposition of the complexes yielding the metal oxides as the final product. The rate constants of the dehydration
and decomposition reactions were determined, from which some kinetic parameters were evaluated. The DTA curves show that the
dehydration of the metal complexes is an endothermic reaction. In all cases the anhydrous metal complexes undergo exothermic
decomposition reactions to give the metal oxide. The thermodynamic parameters (ΔE, ΔH, ΔS, ΔG) for the occurring processes
are calculated. The electrical conductivities of the solid complexes were measured and the activation energy of the complex
and its free ligand are also calculated.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
15.
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. 相似文献
16.
Two bis(bipyridine) polymeric metal nitrate complexes
with 4,4’-bipyridine of simple formula like [M(bipy)2](NO3)2⋅xH2O (where M=Co, Ni and Cu; x=4, 2 and 0, respectively) have been prepared and
characterized. Their thermal decomposition has been undertaken using simultaneous
TG-DTG-DTA and DSC in nitrogen atmosphere and non-isothermal TG in air atmosphere.
Isothermal TG has been performed at decomposition temperature range of the
complexes to evaluate the kinetics of decomposition by applying model-fitting
as well as isoconversional method. Possible mechanistic pathways have also
been proposed for the thermolysis. Ignition delay measurements have been carried
out to investigate the response of these complexes under the condition of
rapid heating. 相似文献
17.
L. Tian N. Ren J. J. Zhang H. M. Liu S. J. Sun H. M. Ye K. Z. Wu 《Journal of Thermal Analysis and Calorimetry》2010,99(1):349-356
The two complexes of [Ln(CA)3bipy]2 (Ln = Tb and Dy; CA = cinnamate; bipy = 2,2′-bipyridine) were prepared and characterized by elemental analysis, infrared
spectra, ultraviolet spectra, thermogravimetry and differential thermogravimetry techniques. The thermal decomposition behaviors
of the two complexes under a static air atmosphere can be discussed by thermogravimetry and differential thermogravimetry
and infrared spectra techniques. The non-isothermal kinetics was investigated by using a double equal-double steps method,
the nonlinear integral isoconversional method and the Starink method. The mechanism functions of the first decomposition step
of the two complexes were determined. The thermodynamic parameters (ΔH
≠
, ΔG
≠
and ΔS
≠
) and kinetic parameters (activation energy E and the pre-exponential factor A) of the two complexes were also calculated. 相似文献
18.
Lucica Viorica Ababei Angela Kriza Adina Magdalena Musuc Cristian Andronescu Elena Adina Rogozea 《Journal of Thermal Analysis and Calorimetry》2010,101(3):987-996
New complexes of 2-benzoyl-pyridil-isonicotinoylhydrazone (L) with Cu(II), Co(II), Ni(II) and Mn(II), having formula of type
[ML2] SO4·xH2O (M = Cu2+, Co2+, Ni2+, x = 2 and M = Mn2+, x = 3), have been synthesised and characterised. All complexes were characterised on the basis of elemental analyses, IR spectroscopy,
UV–VIS–NIR, EPR, as well as thermal analysis and determination of molar conductivity and magnetic moments. The thermal behaviour
of complexes was studied using thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry
(DSC). The structure of L hydrazone was established by X-ray study on single crystal. The ligand works as tridentate NNO,
being coordinated through the azomethine nitrogen, the pyridine nitrogen and carbonylic oxygen. Heats of decomposition, ΔH, associated with the exothermal effects were also determined. 相似文献
19.
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. 相似文献
20.
N. A. Santos R. Rosenhaim M. B. Dantas T. C. Bicudo E. H. S. Cavalcanti A. K. Barro I. M. G. Santos A. G. Souza 《Journal of Thermal Analysis and Calorimetry》2011,103(2):501-506
The synthesis of pigments from the system Ce1−x
O2–M
x
O (M = Cu, Co) was achieved via a polymeric precursors method, Pechini method. Differential scanning calorimetry (DSC) and
thermogravimetry (TG) techniques were used to accurately characterize the distinct thermal events occurring during synthesis.
The TG and DSC results revealed a series of decomposition temperatures due to different exothermal events, which were identified
as H2O elimination, organic compounds degradation, and phase formation. X-Ray diffraction patterns show the presence of pure cubic
CeO2 phase for the samples with low Cu and Co loading. A decrease of the specific surface area with increasing copper and cobalt
content was observed. The UV–visible diffuse reflectance technique was employed to study the optical properties in the 200–800 nm
range. Colorimetric coordinates L*, a*, b* were calculated for the pigment powders. The powders presented a variety of colors from yellow for pure CeO2, to brown for the ones loaded with copper and gray for the ones with cobalt. 相似文献