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1.
The complex [Ru(II)(dcbpyH2)(bdmpp)NCS](PF6) (1) (where dcbpyH2 is 2,2′-bipyridine-4,4′-dicarboxylic acid, bdmpp is 2,6-bis(3,5-dimethyl-N-pyrazoyl)pyridine,) is synthesized and characterized extensively by 1H NMR and 13C NMR 1D and 2D, mass spectroscopy, cyclic voltammetry, electronic absorption spectroscopy and IR. The half-wave potential of the Ru(II)/Ru(III) redox couple was measured at E1/2=+0.795 V versus Ag/AgCl in CH3CN. The complex presents three intense metal-to-ligand charge transfer (MLCT) (dM→πL*) absorption bands centered at 383 (=21 300 M−1 cm−1), 432 (=22 400 M−1 cm−1) and 475 nm (=23 400 M−1 cm−1), respectively. The absorbance is extremely strong between 400 and 500 nm and even at 620 nm, the extinction coefficient is still high (=3768 M−1 cm−1). The strong π-acceptor property of the trans-isothiocyanate ligand compared with the Cl ligand is probably the cause of the blue-shift observed in complex 1. These properties make the complex potentially promising for the photosensitization process. The incorporation of TiO2 photoelectrodes derivatized with this complex into a solar cell using a composite polymer/inorganic oxide solid-state electrolyte confirmed its sensitizing ability. Incident monochromatic photon-to-current conversion efficiency (IPCE) values of about 30% and overall energy conversion efficiency (η) of 1.7% were obtained.  相似文献   

2.
The N2 and H2 evolution, respectively, were monitored during deposition of Pd and Cu from electroless plating baths to obtain in-process control of the composition during preparation of 3–7 μm thick PdCu membranes on tubular ceramic substrates. Compositions estimated by gas evolution compare favorably to those measured in post-mortem XRD and EDS analyses, mostly differing by not more than 1 at.%. This result suggests that use of gas evolution measurements to enable in-process control of composition to within 1 at.% is feasible. Annealing experiments in an H2 atmosphere demonstrated that, at 893 K, only 48 h are needed to form a stoichiometrically homogeneous, 9.5 μm thick, face centered cubic (fcc) Pd63Cu37 membrane from sequentially deposited layers; at 723 K, the same transformation requires over 2 weeks. The appearance of transient body centered cubic (bcc) and fcc phases with lower Pd contents signaled compositional segregation in the initial stages of alloy formation at 723 and 773 K and could be a source of persistent stoichiometric heterogeneity particularly in bcc PdCu membranes. The H2 fluxes of fcc Pd58Cu42 and Pd70Cu30 membranes were JH2=(1.6±1.1) mol m−2 s−1 exp[(−24.8±0.4)kJ mol−1/RT] and JH2=(3.7±0.6) mol m−2 s−1 exp[(−21.3±1.0)kJ mol−1/RT], respectively, at 100 kPa H2 pressure difference.  相似文献   

3.
A new layered gallium phosphate Ga10(PO4)2(HPO4)12(OH)52.5N4C6H204.5H2O was hydrothermally synthesized at 180 °C for 3 days by using triethylenetetramine (teta) as structure-directing agent. Its structure was determined by single-crystal X-ray diffraction with a triclinic cell in the space group P-1 (no 2) with a=8.4718(1) Å, b=18.5915(1) Å, c=24.1994(3) Å, α=110.538(1)°, β=93.656(1)°, γ=93.549(1)° and V=3547.45(6) Å3. It consists of [Ga10(PO4)2(HPO4)12(OH)5]5− macroanionic sheets composed of infinite chains of GaO4(OH)2 octahedra connected via corner-sharing to PO4 and GaO4 tetrahedra. They contain four-, seven- and nine-membered rings. The inorganic layers are held together through hydrogen bond between the terminal PO bondings, the water molecules and the terminal ammonium groups of the intercalated teta molecules.  相似文献   

4.
A new electroanalytical methodology was developed for the quantification of the phytohormone indole-3-acetic acid (IAA), using a graphite–polyurethane composite electrode (GPU) and the square wave voltammetry (SWV), in 0.1 mol L− 1 phosphoric acid solution (pH 1.6). Analytical curves were constructed under optimized conditions (f = 100 s− 1, a = 50 mV, Ei = 5 mV) and the reached detection and quantification limits were 26 μg L− 1 and 0.2 mg L− 1, respectively. The developed methodology is simple and accurate for the routine determination of IAA. In order to verify the application of the electroanalytical methodology in fortified soil samples without previous treatment, an IAA assay was performed without serious interferences of the soil constituents.  相似文献   

5.
In this paper, a sensitive flow injection chemiluminescence system luminol–myoglobin was described for determining femtogram nitrite. Nitrite bound myoglobin producing the ferric heme nitrite complexes, which catalyzed the electron transfer of luminol to myoglobin leading to fast chemiluminescence. The chemiluminescence intensity in the presence of nitrite was remarkably enhanced compared with that in the absence of it. Under the optimum reaction conditions the chemiluminescence increment produced was proportional to the concentration of nitrite in the range of 0.05 pg ml− 1–1.0 ng ml− 1 (R2 = 0.9991), with a detection limit (3σ) of 20.0 fg ml− 1. At the flow rate of 2.0 ml min− 1, the whole process including sampling and washing could be completed in 0.5 min offering the sampling efficiency of 120 h− 1 accordingly, and the relative standard deviation (RSD) was less than 2.60% (n = 5). It was satisfactory for the application to determine nitrite in human urine samples, and the possible mechanism was proposed.  相似文献   

6.
The hydrothermal reaction of 3,5-pyridinedicarboxylic acid (pydcH2) and Co(NO3)2 or Ni(NO3)2 in the presence of 4,4′-bipyridine results in two novel compounds Co(pydc)(H2O)2 (1) and Ni(pydc)(H2O) (2). Crystal data: 1, monoclinic, C2/c, a=9.900(2), b=11.984(2), c=7.3748(15) Å, β=105.37(3)°, V=843.7(3) Å3, Z=4; 2, monoclinic, P21/c, a=7.7496(6), b=15.0496(11), c=6.4224(5) Å, β=108.437(1)°, V=710.59(9) Å3, Z=4. The structure of 1 is composed of honeycomb layers built up from {CoO4N} trigonal bipyramids and 3,5-pyridinedicarboxylate bridges. The structure of 2 adopts a three-dimensional framework structure in which the Ni atoms are coordinated by the pydc bridges both within the honeycomb layer and between the layers. The magnetic properties of 1 and 2 have been investigated.  相似文献   

7.
The removal of heavy metal cations by natural zeolites   总被引:4,自引:0,他引:4  
In this study, the adsorption behavior of natural (clinoptilolite) zeolites with respect to Co2+, Cu2+, Zn2+, and Mn2+ has been studied in order to consider its application to purity metal finishing wastewaters. The batch method has been employed, using metal concentrations in solution ranging from 100 to 400 mg/l. The percentage adsorption and distribution coefficients (Kd) were determined for the adsorption system as a function of sorbate concentration. In the ion exchange evaluation part of the study, it is determined that in every concentration range, adsorption ratios of clinoptilolite metal cations match to Langmuir, Freundlich, and Dubinin–Kaganer–Radushkevich (DKR) adsorption isotherm data, adding to that every cation exchange capacity metals has been calculated. It was found that the adsorption phenomena depend on charge density and hydrated ion diameter. According to the equilibrium studies, the selectivity sequence can be given as Co2+ > Cu2+ > Zn2+ > Mn2+. These results show that natural zeolites hold great potential to remove cationic heavy metal species from industrial wastewater.  相似文献   

8.
The electronic spectra of solid iron(III) vanadates FeVO4 and Fe2V4O13 were investigated by the diffuse reflectance technique in the spectral range 12 500–50 000 cm−1. The spectra of investigated vanadates contain 2–3 intensive CT bands in the UV region and two lowest energy dd bands in the 12 000–22 000 cm−1 range. The presence of the weak bands for FeVO4 and Fe2V4O13 at 16 500 cm−1 and 20 500 cm−1 points to the lattice deffects (oxygen deficiency and the presence of the V4+ ions) in the structure of investigated vanadates.  相似文献   

9.
The mixed lead nitrate oxalate, Pb2(NO3)2(C2O4).2H2O, has been obtained in a polycrystalline form in the course of a study on precursors of nanocrystalline PZT-type oxides. Its crystal structure has been solved from powder diffraction data collected using a monochromatic radiation from a conventional X-ray source. The symmetry is monoclinic, space group P21/c (No. 14), the cell dimensions are a=10.623(2) Å, b=7.9559(9) Å, c=6.1932(5) Å, β=104.49(1)° and Z=4. The structure consists of a stacking of complex double sheets parallel to (1 0 0), forming layers held together by hydrogen bonds. The sheets result from the condensation of PbO10 polyhedra, in which the oxalate and nitrate groups, as well as water molecules, play a major role. The structure is discussed in terms of Pb---O distances, polyhedra shape and lead coordination, with emphasis on the dimensional polymerisation role of water molecules. The thermal behaviour of this layered compound is carefully described from temperature-dependent powder diffraction and thermogravimetric measurements. The enthalpy, ΔrH=232(3) kJ mol−1, and entropy, ΔrS=532(8) J K−1 mol−1, of the dehydration reaction have been determined. The high value of ΔrH demonstrates that the water molecules are strongly bonded in the structure. The complex decomposition proceeds through the crystallisation and decomposition of Pb(NO3)2(C2O4) into Pb(NO3)2 and PbC2O4, and, finally, various lead oxides.  相似文献   

10.
Chemical preparation, X-ray single crystal, thermal analysis and IR spectrometric investigation of (C9H15N3O2)SO4 denoted LTHS are described. The LTHS crystallizes in the monoclinic system with P21 space group. Its unit cell dimensions are a=5.5386(1) Å, b=8.0467(4) Å, c=14.0780(6) Å, β=93.339(3)° with V=626.36(4) Å3 and Z=2. The structure has been solved using direct method and refined to a reliability R factor of 0.0212. The LTHS structure is built up from organic chains parallel to the b axis, linked via N---H…O hydrogen bonds and interconnected by inorganic groups so as to build a three-dimensional arrangement.  相似文献   

11.
An equipment for the determination of mutual diffusion coefficients using the Taylor's dispersion technique is described. The radius of the capillary was determined with the help of various calibration methods. Diffusion coefficients of aqueous tetraalkylammonium perchlorates, Me4NClO4, and Et4NClO4, were measured at 25°C in the concentration range 10–3 to 5×10–2 mol-dm–3, and the slightly soluble Pr4NClO4 up to 1×10–2 mol-dm–3. The slope of linear plots ofD vs. is in agreement with theory, in contrast to the limiting valuesD 0, which all deviate by about –5% from the Nernst-Hartley values.  相似文献   

12.
The products of ascorbic acid oxidation in the presence of cobalt octa-4,5-carboxy-phthalocyanine sodium salt (TPH) were identified. These include the ascorbate radical (A·), hydroxyl radical (OH·), and hydrogen peroxide (H2O2). The kinetics of accumulation and consumption of the reaction products was studied. For the concentration ranges of ascorbic acid = 0–2.5 ⋅ 10−3 mol L−1 and the catalyst C TPH = 0–3.5 ⋅ 10−5 mol L−1, the the highest possible concentration of the ascorbate radical is ∼10−7 mol L−1, the concentration of H2O2 is 7 ⋅ 10−4 (30% of the starting concentration of ascorbic acid) and the concentration of the hydroxyl radical is at most 10−6 mol L−1.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2224–2228, October, 2004.  相似文献   

13.
Occurrence of ochratoxin A in Turkish wines   总被引:1,自引:0,他引:1  
I. Var  B. Kabak   《Microchemical Journal》2007,86(2):241-247
A total of 95 wine samples including 34 white, 10 rosé and 51 red wines originating from four different Turkish areas were analysed for ochratoxin A (OTA). An analytical method based on immunoaffinity column (IAC) for clean-up and high performance liquid chromatography with fluorescence detection (HPLC-FD) was used to determine OTA in wines. The limit of detection (LOD) was estimated as 0.006 ng ml− 1 for white wine and 0.010 ng ml− 1 for rosé and red wines. The limit of quantification (LOQ) was estimated as 0.020 ng ml− 1 in white wine and 0.030 ng ml− 1 in rosé and red wines. Recovery experiments were carried out with spiked samples in the range 0.1–1 ng ml− 1 of OTA. The average OTA recoveries from spiked white wine samples varied from 79.43% to 85.07%; while the mean recoveries for rosé and red wine samples were in the range of 77.48–83.96% and 76.61–83.55%, respectively. OTA was detected in 82 (86%) wine samples at levels of < 0.006–0.815 ng ml− 1, which were below the maximum allowable limit established by the European Community. The mean OTA concentration in red wines was slightly higher than in white and rosé wines. Furthermore, our data indicate that the geographic region of origin has strong influence on OTA level for white, rosé and red wines: wines originating from Thrace (n = 44, mean = 0.158 ng ml− 1) and Aegean (n = 28, mean = 0.060 ng ml− 1) regions of Turkey were more contaminated with OTA compared with wines originating from central (n = 15, mean = 0.027 ng ml−1) and east Anatolia (n = 8, mean = 0.027 ng ml− 1) areas. This study showed that the occurrence of OTA in Turkish wines is high, but at levels that probably leads to a non-significant human exposure to OTA by consumption of wines.  相似文献   

14.
The hydrothermal synthesis, crystal structure and some properties of a zinc phosphite with a neutral cluster, [Zn(2,2′-bipy)]2(H2PO3)4, are reported. This compound crystallizes in the triclinic system of space group P-1 (No. 2), a=8.3067(5) Å, b=8.9545(4) Å, c=10.0893(6) Å, α=95.448(2)°, β=99.7530(10)°, γ=103.461(2)°, V=712.23(7) Å3, Z=1. The cluster consists of 4-membered rings formed by alternating ZnO3N2 square pyramids and H2PO3 pseudo pyramids, with two “hanging” H2PO3 groups attached to each of the Zn centers. The clusters are linked together by extensive multipoint hydrogen bonding involving the phosphite units to form a sheet-like structure. This compound represents the first example of zinc phosphite with P---OH bonds. An intense photoluminescence was observed from this compound upon photoexcitation at 388 nm.  相似文献   

15.
IR spectra of 3 normal solutions of 14 different salts [chlorides of Al+++, Be++, Mg++, Ca++, Sr++, Ba++, Zn++, Cd++, Li+, Na+, K+, Rb+, Cs+, N(CH3) 4 + ] in both, 96% H2O+4% D2O and 100% H2O, were measured in the frequency range =2 800–2 100 cm–1. From up to 18 single measurements for each solution the frequencies and halfwidths of the O-D stretching bands of isotopically dilute HDO were determined with high accuracy. Frequencies in the range =2 510–2 529 cm–1 and halfwidths in the range =155–205 cm–1 resulted atT=30°C with standard deviations typical less than ±1 cm–1 and ±4 cm–1, respectively. An almost perfect correlation between the O-D stretching band parameters and the polarizing power of the cations was obtained.Herrn Prof. Dr.A. Neckel, Wien, zum 60. Geburtstag gewidmet.  相似文献   

16.
Dielectric studies performed on the solid solution Ba1−xNaxTi1−xNbxO3 (BNTN) show that all compositions (x= 0.1, 0.15, 0.2, 0.4, 0.5 and 0.025, 0.05, 0.6, 0.7, 0.8) exhibit a ferroelectric–paraelectric phase transition where the Curie temperature is a function of the composition. The specimens with composition BNTN (x= 0.05, 0.1, 0.15, 0.2) have been refined by the Celref method from X-ray powder diffraction data. The evolution of dielectric constant as a function of temperature and frequency in the range 77–500 K and 20–2 × 105 Hz, respectively, show that these ceramics present the classical ferroelectric character when 0x<0.075 and 0.55<x1 and relaxor character when 0.075x0.55.  相似文献   

17.
The local structure in molten YF3–LiF and LaF3–LiF binaries has been investigated by NMR and EXAFS spectroscopy. For YF3–LiF, the high-temperature 19F and 7Li NMR spectra have been recorded in situ in the molten state for compositions ranging from pure LiF to pure YF3. The LaF3–LiF system has been studied by 19F and 139La NMR and EXAFS spectroscopy at the LIII edge of La. The local environment around the La3+ in the molten state does not depend on the composition, while 19F chemical shift evolution confirms the progressive formation of bridged species. To cite this article: A.-L. Rollet et al., C. R. Chimie 7 (2004).

Résumé

Étude in situ par spectroscopies RMN et EXAFS à haute température de fluorures de terres rares fondus. La structure locale des mélanges fondus YF3–LiF et LaF3–LiF a été étudiée par spectroscopies RMN et EXAFS à haute température. Pour le système YF3–LiF, les spectres RMN à haute température de 19F et 7Li ont été enregistrés in situ dans le liquide pour différentes compositions variant de LiF pur à YF3 pur. Le système LaF3–LiF a été étudié par RMN de 19F et 139La, et par EXAFS au seuil LIII du lanthane. L’environnement autour du La3+ à l’état fondu ne dépend pas de la composition, alors que les évolutions du déplacement chimique du fluor confirment la formation progressive d’espèces pontantes. Pour citer cet article : A.-L. Rollet et al., C. R. Chimie 7 (2004).  相似文献   

18.
The potential functions of internal rotation around the C -S bond in the C6H5S(O)CH3 and C6H5S(O)CF3 molecules were obtained by ab initio MP2(full)/6-31+G* calculations. The stationary points were identified by solving the vibrational problems. The structures in which the plane of the C -S-C bonds is approximately perpendicular to the benzene ring plane correspond to the energy minimum. The barriers to rotation around the C -S bond, corrected for the zero-point vibration energy, are 21.29 [C6H5S(O)CH3] and 28.98 [C6H5S(O)CF3] kJ mol−1. The bond angles (deg) are as follows: 95.7 (CSC), 107.1 (C SO), 106.3 (C SO) in C6H5S(O)CH3; 93.5 (CSC), 108.2 (C SO), 105.2 (C SO) in C6H5S(O)CF3. The bond lengths are as follows (Å): 1.520 (S=O), 1.804 (C -S), 1.810 (C -S) in C6H5S(O)CH3; 1.507 (S=O), 1.799 (C -S), 1.870 (C -S) in C6H5S(O)CF3. According to the results of NBO calculations, the formally double S=O bond consists of a strongly polarized covalent σ bond (S→O) and an almost ionic bond. An increase in the S=O bond multiplicity relative to a single bond is mainly due to hyperconjugation by the mechanism n(O)→σ*(C -S) and n(O)→σ*(C -S) and, to a lesser extent, by interaction of the oxygen lone electron pairs with the Rydberg orbitals of the S atoms, characterized by a large contribution of the d component.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 1, 2005, pp. 96–104.Original Russian Text Copyright © 2005 by Bzhezovskii, Il’chenko, Chura, Gorb, Yagupol’skii.  相似文献   

19.
A method for the analysis of precise gas solubility data is presented and applied to new determinations of the Henry constant, k2, for He, Ne, Ar, Kr, and Xe. The values of k2 are fitted to the same sets of temperature functions which we have tried for oxygen. Our previously proposed power series in 1/T, ln(k2/P )=a0+a1/T+a2/T2 (Mark I), gives the best 3-term fit within the temperature range 0–60°C. For use over the full range to the critical temperature of water, we have discovered a new function given by (T*)2ln(k2/P )=A0(T*)2+A1(1-T*)1/3+A2(1-T*)2/3(Mark II), where T*T/T c1 . It fits our data from 0–60°C nearly as well as Mark I; it fits high temperature data from other sources; and at the critical temperature of water it satisfies theoretical requirements. Expansion of Mark II reveals the relationship between Mark II and Mark I and leads to a 4-term smoothing function, ln(k2/P )=a–2(T*)–2+a–1(T*)–1+a0+a1T* (Mark III), which we believe gives the best values only for the 0–60°C range. Mark III is used to calculate values for , and , 0–60°C, and a procedure is empolyed to estimate the errors. Agreement is excellent between these results and those obtained from precise microcalorimetric measurements made by others. With the inclusion of pressure correction terms, Mark II yields the four thermodynamic function changes for use at high temperatures. With increasing temperature, these changes suddenly turn upward toward plus infinity as T c1 is approached. Essentially direct determinations of for argon by other workers are in excellent agreement with our results. The symmetrical activity coefficient at infinite dilution, 2 ° is examined and the hypothetical properties of k2 are explored below 0°C. Mark II can be expressed in the reduced form (T*)2ln(k 2 * )=A1(1-T*)1/3+A2(1-T*)2/3, where k 2 * k 2/(p c12c1). A2 is a very good linear fit to A1, which suggests a characteristic temperature for water at 287.3 K.  相似文献   

20.
In-capillary derivatization and field-amplified sample injection (FASI) coupled to capillary zone electrophoresis (CZE) was evaluated for the analysis of metals (Co(II), Cu(II), Ni(II), and Fe(II)) using 2-(5-Nitro-2-Pyridylazo)-5-(N-Propyl-N-Sulfopropylamino)Phenol (Nitro-PAPS) as the derivatizing agent. For FASI, the optimum conditions were water as sample solvent, 1 s hydrodynamic injection (0.1 psi) of a water plug, 5 s of electrokinetic introduction (10 kV) of the sample. The in-capillary derivatization was successfully achieved with zone-passing strategy in order tandem injection of Nitro-PAPS reagent (0.5 psi, 7 s), a small water plug (0.1 psi, 1 s), and metal ion introduction (10 kV, 5 s). The solution of 45 mmol L− 1 borate pH 9.7 and 1.0 × 10− 5 mol L− 1 Nitro-PAPS containing 20% acetonitrile was used as the running buffer. The limit of detection obtained by the proposed method was lower than those from pre-capillary derivatization about 3–28 times. The recovery of the method was comparable to pre-capillary derivatization method. In-capillary derivatization-FASI-CZE was applied to analysis of metals in wine samples. The results were compared with those obtained by CZE with pre-capillary derivatization method and atomic absorption spectrometry (AAS).  相似文献   

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