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1.
The new zinc(II) complexes of general formula Zn(CH 3CH 2CH 2COO) 2· nL (where L = caffeine, nicotinamide, theobromine; n=1 or 2) were prepared and identified.Thermal properties of these compounds were investigated by thermal analysis (TG/DTG, DTA, DSC/DDSC).Gaseous products of thermal decomposition were detected by IR spectroscopy and Mass spectroscopy. Final products of thermal decomposition were determined by X-ray powder diffraction patterns.This work was supported by the Slovak Ministry of Education Grant No. 1/3230/96. This financial support is gratefully acknowledged. 相似文献
2.
Three
new complex compounds of general formula Zn{4-ClC 6H 3-2-(OH)COO} 2⋅ L2⋅ nH 2O
(where L=thiourea (tu), nicotinamide (nam),
caffeine (caf), n=2,3), were prepared and
characterized by chemical analysis, IR spectroscopy and their thermal properties
were studied by TG/DTG, DTA methods. It was found that the thermal decomposition
of hydrated compounds starts with the release of water molecules. During the
thermal decomposition of anhydrous compounds the release of organic ligands
take place followed by the decomposition of salicylate anion. Zinc oxide was
found as the final product of the thermal decomposition performed up to 650°C.
RTG powder diffraction method, IR spectra and chemical analysis were used
for the determination of products of the thermal decomposition. 相似文献
3.
Five new complex compounds of general formula Zn(Hsal) 2·L 2·nH 2O (where Hsal=OHC 6H 4COO -, L=thiourea (tu), nicotinamide (nam), caffeine (caf), theobromine (tbr), n=2-4), were prepared and characterized by chemical analysis, IR spectroscopy and studied by methods of thermal analysis (TG/DTG,
DTA). It was found that the thermal decomposition of hydrated compounds starts with the release of water molecules. During
the thermal decomposition of anhydrous compounds the release of organic ligands take place followed by the decomposition of
salicylate anion. Zinc oxide was found as the final product of the thermal decomposition heated up to 800°C. RTG powder diffraction
method, IR spectra and chemical analysis were used for the determination of products of the thermal decomposition.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
A new Zn(II) 2-chlorobenzoate complex, [Zn(2-ClC 6H 4COO) 2(nad) 2] (nad = nicotinamide), was synthesized and characterized by elemental analysis, infrared (IR) spectroscopy, mass spectrometry, thermal analysis, and X-ray structure determination. The mechanism of thermal decomposition of the complex was studied by TG/DTG, DTA, IR spectroscopy, and mass spectrometry. The thermal decomposition is characterized as a two-step process. Zinc oxide was found as the final product of the thermal decomposition performed up to 900°C. Mass spectrometry was used to determine the volatiles released during thermal decomposition. The IR spectrum indicates that carboxylate is coordinated to zinc in monodentate coordination. [Zn(2-ClC 6H 4COO) 2(nad) 2] crystallizes in the monoclinic system, space group Pn, a = 10.376(2) Å, b = 10.100(1) Å, c = 12.604(1) Å, β = 100.79(1)°. The zinc is tetrahedrally coordinated by two nitrogens of nicotinamide and two oxygens of 2-chlorobenzoate. 相似文献
5.
Four cocoa powder varieties processed in different European countries (Germany, Poland, Romania and Bulgaria) were subjected to physicochemical, phytochemical and microbiological analysis. The cocoa powders were extensively characterized by recording their pH and titratable acidity, respectively, the polyphenols and also the methylxantine derivatives content (theobromine and caffeine). The cocoa powders pH ranged between 5.37 and 8.23, while the titratable acidity was 3.2–4.3 miliequivalent (100 g)?1 of cocoa powder. Their total polyphenols content ranged between 0.986?÷?2.003 g GAE/(100 g)?1. The methylxanthine derivatives (theobromine and caffeine) were analyzed by the HPLC method and ranges of 0.992–1.174% for theobromine and 0.096–0.369% for caffeine were obtained. Thermal analysis (TG–DTA) combined with mass spectrometry (MS) elucidated the decomposition processes and the volatile substances (CO, CO2, H2O, NO, theobromine, caffeine). The thermal analysis revealed transformations in the cocoa powders composition: drying and water loss; decomposition of pectic polysaccharides; lipids, amino acids and proteins, crystalline phase transformations and carbonizations. The microbiological analysis tested the degree of preservation of the cocoa powders across time, specifically immediately after unwrapping and after 14 days. 相似文献
6.
Coumarilate–nicotinamide complexes of Co II and Zn II were synthesized and investigated by elemental analysis, magnetic susceptibility, solid state UV–Vis, direct injection probe mass spectra, FTIR spectra, thermoanalytic TG-DTG/DTA, and crystal X-ray diffraction methods. It was obtained that both complex structures contain 2 mol aqua ligands, 2 mol coumarilate (CCA ?) and 2 mol nicotinamide (NA) ligands per formula unit. The CCA ? and NA ligands were bonded to metal cations as monodentate through acidic oxygen and nitrogen of pyridine ring, respectively. Thermal decomposition of each complex starts with dehydration and continue removing of 1 mol NA ligand. The thermal dehydration of the complexes takes place in one or two steps. The decomposition mechanism and thermal stability of the investigated complexes are interpreted in terms of their structures. The final decomposition products are found to be metal oxides. 相似文献
7.
Thermogravimetry (TG), differential thermal analysis (DTA) and other analytical methods have been applied to the investigation
of the thermal behaviour and structure of the complexes Mg(pc)(na) 3⋅3H 2O (I), Mg(pc)(py) 2⋅2H 2O (II),Mg(pc)(pic) 2⋅2H 2O (III) and Mg(pc)(caf) 2⋅4H 2O (IV), where pc=2,6- pyridinedicarboxylate, na=nicotinamide, py=pyridine, pic=γ-picoline and caf=caffeine. The thermal decomposition of these compounds is multi-stage processes. The chemical composition of the complexes,
the solid intermediates and the resultant products of thermolysis have been identified by means of elemental analysis and
complexometric titration. Schemes of destruction of these complexes are suggested. Heating of these compounds first resulted
in a release of water molecules. In complexes I, II and IV the loss of the molecular ligands (na, py and caf) occur (on the
TG curves) in one step (-2na, -2py and -2caf) and in complex III in two steps (-pic, -pic). The final product of the thermal
decomposition was MgO. The thermalstability of the complexes can be ordered in the sequence: IV<I<III<II. Nicotinamide, pyridine,
γ-picoline and caffeine were co-ordinated to Mg(II) through the N atom of the respective heterocyclic ring. IR data suggested
a unidentate co-ordination of carboxylates to Mg(II) in complexes I–IV.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
Thermal behaviour of mechanochemically synthesized nanocrystalline CuS particles by high-energy milling in an industrial mill has been studied. Structure properties were characterized by X-ray powder diffraction that reveals the formation of copper sulphide CuS as well as of copper sulphate CuSO 4·5H 2O. Thermal properties of the as-prepared products were studied by the differential scanning calorimetry together with X-ray inspection for detection by pass products formed. The decomposition of the as-prepared sample has been studied too. Thermal stability of the anhydrous CuSO 4 formed by the thermal decomposition is lower than the thermal stability of non-milled samples. The final product of the thermal decomposition is metallic copper instead of Cu 2O, which is stable up to 1100 °C. Differential scanning calorimetry (DSC) analysis proved that the percentage of chalcantite in the covellite mechanochemically synthesized by high-energy milling is 48-51%. 相似文献
9.
New zinc(II) propionate complexes (CH 3CH 2COO) 2Zn·Ln·xH 2O, where n=1-2, x=0 or 2, were prepared by reaction of zinc(II) propionate with heterocyclic ligands ( L=theophylline, nicotinamide, methyl-3-pyridyl carbamate) and their thermal properties were studied. The prepared complex compounds were characterized by elemental analysis and IR spectra. TG/DTG and DTA measurements of the prepared compounds were performed in the air atmosphere under dynamic conditions. The thermal decomposition can be characterized as a multi-step process. The first step is attributed to the elimination of water or N-donor ligand molecules. It is followed by the decomposition of propionate anion when diethyl ketone and carbon dioxide were released. Zinc oxide was found as a final product of the thermal decomposition of the complex compounds under study. The volatile intermediate products of the thermal decomposition of zinc(II) propionate complexes were identified by IR-spectroscopy, qualitative chemical analyses and final solid product by X-ray powder diffraction method. Moreover, IR spectra suggest monodentate coordination of propionate anion to zinc. The complexes were tested against bacteria and filamentous fungi and show both antimicrobial activity and fungistatic effect towards pathogens as well as probiotic activity towards Lactobacillus paracasei. 相似文献
10.
Thermal decomposition of Bi(SCN) 3, Cd(SCN) 2, Pb(SCN) 2 and Cu(SCN) 2 has been studied. The thermal analysis curves and the diffraction patterns of the solid intermediate and final products of the pyrolysis are presented. The gaseous products of the decomposition (SO 2 and CO 2) were detected and quantitatively determined. Thermal, X-ray and chemical analyses have been used to establish the nature of the reactions occurring at each stage in the decomposition.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
11.
Thermogravimetry (TG), derivative thermogravimetry (DTG) and infrared (IR) spectroscopy have been applied to the investigation of the thermal behaviour and structure of the compounds [Cu(2-Clbz) 2(nia) 2(H 2O) 2] (I), [Cu(2-Clbz) 2(nia) 2]·H 2O (II), [Cu(2-Brbz) 2(nia) 2]·2H 2O (III), [Cu(2-Brbz) 2(nia) 2(H 2O)] (IV), where 2-Clbz and 2-Brbz?=?2-chloro- and 2-bromobenzoate anions, nia?=?nicotinamide, H 2O?=?water molecules. Thermal decomposition of all studied compounds proceeds in three steps. Heating the compounds first results in a release of non-coordinated and/or coordinated water molecules. The final product of thermal decomposition was CuO. The thermal stability of the complexes can be ordered in the sequence: I<IV<III<II. Nicotinamide is coordinated to Cu(II) through the nitrogen atom of the heterocyclic ring. IR data suggest the unidentate coordination of benzoate anions to Cu(II) in complexes I, IV and bidentate coordination in complexes II and III. 相似文献
12.
New zinc(II) 4-bromobenzoate complex compounds with general formula [Zn(4-BrC 6H 4COO) 2L 2]· xH 2O (where L?=?urea, nicotinamide, phenazone or thiourea, x?=?0?C2) were prepared and characterized by elemental analysis, IR spectroscopy and thermal analysis. The thermal decomposition of hydrated compounds started with dehydration process. During the thermal decomposition, the neutral organic ligand, bis(4-bromophenyl)methanone and carbon dioxide were evolved. The solid intermediates and volatile products of thermal decomposition were proved by IR spectroscopy and mass spectrometry. The final solid product of the thermal decomposition heated up to 800?°C was zinc oxide, which was confirmed by X-ray powder diffractometry. Antimicrobial activity of the prepared compounds was tested against various strains of bacteria, yeasts and filamentous fungi ( E. coli, S. aureus, C. albicans, R. oryzae, A. alternata and M. gypseum). It was found that bacterium S. aureus and fungi A. alternata are the most sensitive to the studied compounds. 相似文献
13.
The thermal decomposition process of La 2O 3/MgO (La/Mg = 2, 1 and 0.5) supported nickel (15% mass/mass Ni) precursor was investigated. Thermal analysis results show
distinct processes of decomposition of the samples in accordance with the composition. The mass loss at higher temperature
is associated to distinct stages of decomposition of lanthanum precursors. The thermal analysis results agree with the FTIR
spectra showing change in the band corresponding to carbonates and nitrates species. XRD results also confirmed the precursor’s
decomposition. It can be concluded that the thermal decomposition of La 2O 3–MgO-nickel precursor depends on the La/Mg ratio and of the residual species. 相似文献
14.
The thermal properties of some organotin complexes of general structure (4-ZC 6H 4) 2SnCl 2.L 2 (Z=Me, CF 3, F, Cl, OMe and H; L 2 = 2,2′ -bipyridyl and 4,4′ -dimethyl-2,2′ -bipyridyl) are reported. The thermal data obtained by Differential Thermal Analysis (DTA) for these complexes is reported. Thermal decomposition experiments for some of the complexes are described and indicate a disproportionation of the complexes into the aryltin trichloride complex and the triaryltin chloride. The controlled decomposition provides a possible alternative preparative route to some aryltin trichloride complexes. 相似文献
15.
Novel zinc(II) complex compounds of general formula Zn(C 6H 5COO) 2·L 2 (where L=caffeine (caf) and urea (u)) were synthesized and characterized by elemental analysis and IR spectroscopy. The thermal behaviour
of the complexes was studied during heating in air by thermogravimetry. It was found that the thermal decomposition of the
anhydrous Zn(II) benzoate compounds with bioactive ligands was initiated by the release of organic ligands at various temperatures.
On further heating of the compounds up to 400°C the thermal degradation of the benzoate anions took place. Zinc oxide was
found as the final product of the thermal decomposition of all zinc(II) benzoate complex compounds heated to 600°C. Results
of elemental analysis, infrared spectroscopy, mass spectroscopy and thermogravimetry are presented. 相似文献
16.
New zinc(II) 2-bromobenzoate complex compounds with general formula Zn(2-BrC 6H 4COO) 2· nL· xH 2O (where L = urea, nicotinamide, N-methylnicotinamide, N,N-diethylnicotinamide, isonicotinamide, phenazone n = 0–2, x = 0–2) were prepared and characterized by elemental analysis, IR spectroscopy and thermal analysis. The thermal decomposition
of hydrated compounds started with dehydration process. During the thermal decomposition organic ligand, carbon dioxide and
bis(2-bromophenyl)ketone were evolved. The solid intermediates and volatile products of thermal decomposition were proved
by IR spectroscopy and mass spectrometry. The final solid product of the thermal decomposition heated up to 1073 K was zinc
oxide. Antimicrobial activity of the prepared compounds was tested against various strains of bacteria, yeasts and filamentous
fungi ( E. coli, S. aureus, C. albicans, R. oryzae, A. alternate and M. gypseum). It was found that the selected bacteria were more sensitive to the studied zinc(II) complex compounds than the yeast and
the filamentous fungi. 相似文献
17.
Hydrated methanesulfonates Ln(CH 3SO 3) 3· nH 2O ( Ln=La, Ce, Pr, Nd and Yb) and Zn(CH 3SO 3) 2· nH 2O were synthesized. The effect of atmosphere on thermal decomposition products of these methanesulfonates was investigated.
Thermal decomposition products in air atmosphere of these compounds were characterized by infrared spectrometry, the content
of metallic ion in thermal decomposition products were determined by complexometric titration. The results show that the thermal
decomposition atmosphere has evident effect on decomposition products of hydrated La(III), Pr(III) and Nd(III) methanesulfonates,
and no effect on that of hydrated Ce(III), Yb(III) and Zn(II) methanesulfonates.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
18.
In order to obtain a better understanding of thermal substituent effects in 1,2,4-triazole-3-one (TO), the thermal behavior
of 1,2,4-triazole, TO, as well as urazole and the decomposition mechanism of TO were investigated. Thermal substituent effects
were considered using thermogravimetry/differential thermal analysis, sealed cell differential scanning calorimetry, and molecular
orbital calculations. The onset temperature of 1,2,4-triazole was higher than that of TO and urazole. Analyses of evolved
decomposition gases were carried out using thermogravimetry–infrared spectroscopy and thermogravimetry–mass spectrometry.
The gases evolved from TO were determined as HNCO, HCN, N 2, NH 3, CO 2, and N 2O. 相似文献
19.
Thermal decomposition ranges of Cp 2HfR , (R = Me, Ph) have been found by the DTA method. The thermal stability of hafnium derivatives greatly exceeds the stability of analogous titanium and zirconium compounds. Decomposition of Cp 2HfR 2 occurs by abstraction of σ-bonded groups which convert into RH. Hydrogen donors for the RH formation are both π-cyclopentadienyl and σ-bonded groups. The initial π-Cp 2Hf structure rearranges to form the (η 5-Cp)-(η 5,η 1-C 5H 4)Hf fragment. These react with HCl to produce Cp 2HfCl 2. It has been established that hydrogen exchange between cyclopentadienyl rings and methyl groups occurs during the thermal decomposition of Cp 2HfMe 2. As a result of the exchange process on thermal decomposition of Cp 2HfMe 2- d6, deuterium insertion into the cyclopentadienyl ring has been shown. The participation of solvent during the decomposition process of the hafnium derivatives has been studied. 相似文献
20.
New zinc bromobutyrate complexes of general formula ZnX 2·1−L·nH 2O (X=CH 2Br(CH 2) 2COO −; CH 3CH 2CHBrCOO −) containing one or two molecules of caffeine, nicotin-amide and phenazone as ligands (L) were prepared.
The compounds were characterized by MS-, IR- spectroscopy, chemical and thermal analysis. The thermal decomposition of hydrated
compounds starts by the release of water molecules. In anhydrous compounds the loss of organic ligands takes place followed
by the decomposition of the bromobutyrate anion at higher temperatures. Zinc bromide was found among the final products of
thermal decomposition. Water, carbon monoxide, propylaldehyde, vinylaldehyde and formaldehyde were detected in the gaseous
products of the thermally decomposed samples on heating up to 700°C.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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