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1.
Properties of CF x /Li and CF x /Na cells were examined while using galvanostatic charging/discharging, electrochemical impedance spectroscopy and scanning electron microscopy (SEM). The capacity during the first cycle was as high as ca. 1000 mAh g?1. Such an electrode is suitable for primary CF x /Li and CF x /Na batteries. SEM images of CF x cathode showed that during discharging it was transformed into amorphous carbon and LiF or NaF crystals (of diameter of ca. 5–20 μm). These systems (C?+?LiF or C?+?NaF) cannot be reversibly converted back into CF x /Li or CF x /Na, respectively. Exchange current densities are between 10?7 Acm?2 and 10?9 Acm?2 when working with LiPF6 and NaPF6 electrolytes (1.12?×?10?7 Acm?2 and 6.82?×?10?9 Acm?2, respectively). Those values are low and indicate that the charge transfer process may be the rate-determining step. Activation energies for the charge transfer process were 57 and 72 kJ mol?1 for CF x /LiPF6 and CF x /NaPF6 systems, respectively. Higher activation energy barrier for the CF/Na+?+?e??→?C?+?NaF reaction results in lower observed exchange current density in comparison to the system with lithium ions.  相似文献   

2.
This article presents the determination of thermokinetic parameters and thermodynamic functions from the thermoforming of LiMnPO4. In our previous paper, a couple of thermoreaction processes, e.g., co-elimination and polycondensation of thermokinetics and thermodynamics, were incompletely determined. The co-elimination process is considered as dehydration and a deammoniation process in this paper. Evidently, an alternative technique was applied for calculating the extent of conversion values using the ratio of the peak area of the deconvoluted DTG peak after applying the Fraser–Suzuki deconvolution. An iterative equation of the integral isoconversional technique was used to estimate the reliable activation energy Eα. Each separated peak, including dehydration, deammoniation, and polycondensation, was obviously evaluated as a single kinetic process with its own kinetic parameters. In order to choose reliable mechanisms, the y(α) master plots or the plots between the experiment and the model were compared. The plots thus obtained showed that the dehydration, deammoniation, and polycondensation processes were found to be 3/2-order chemical reaction (F3/2), 2-order chemical reaction (F2), and nucleation (P3/2) mechanisms, respectively. The pre-exponential factor values were obtained from Eα, and the reaction mechanisms were found to be 3.78?×?1012, 7.05?×?1012, and 1.96?×?1013 s?1, respectively. The evaluated thermodynamic data of the activated complexes showed that the thermal reaction required thermal energy to complete the reaction.  相似文献   

3.
The heat capacities of Pb2V2O7 and Pb3(VO4)2 as a function of temperature in the range 350–965 K have been studied by the differential scanning calorimetry method. The CP = f(T) curve for Pb2V2O7 is described by the equation Cp = (230.76 ± 0.51) + (73.60 ± 0.50)×10-3T ? (18.38 ± 0.54)×105T-2 in the entire temperature range. For Pb3(VO4)2, there is a well-pronounced extreme point in the CP = f(T) curve at T = 371.5 K, which is caused by the existence of a structural phase transition. The thermodynamic properties of the oxide compounds have been calculated.  相似文献   

4.
A mixed oxide-covered mesh electrode composed of NiCo2O4 (MOME-NiCo2O4) was prepared on a stainless-steel substrate using thermal decomposition (slow-cooling rate method). Surface, bulk and electrochemical properties of MOME were studied using different techniques, namely scanning electron microscopy (SEM), X-ray diffraction (XRD), cyclic voltammetry (CV) with determination of the electrochemical porosity (?) and morphology factor (φ) parameters, quasi-stationary polarisation curves (PC) and electrochemical impedance spectroscopy (EIS). SEM images revealed a good coverage of the metallic wires by a compact oxide layer (absence of cracks). XRD analysis confirmed the formation of the spinel NiCo2O4 with the presence of NiO. The ‘in situ’ surface parameters denoted as ? and φ exhibited values of 0.39 and 0.33, respectively, revealing that the electrochemically active surface area is mainly confined to the ‘outer/external’ surface regions of the oxide layer. The PC was characterised by two Tafel slopes distributed in the low (b 1 = 46 mV dec?1) and high (b 2 = 59 mV dec?1) overpotential domains. The corresponding apparent exchange current densities were j 0(1) = (3.43 ± 0.11) × 10?6 A cm?2 and j 0(2) = (6.70 ± 0.08) × 10?6 A cm?2, respectively. The EIS study accomplished in the low-overpotential domain revealed a Tafel slope (b 1) of 51 mV dec?1. According to the spin-trapping reaction using N,N-dimethyl-p-nitrosoaniline (RNO), the MOME-NiCo2O4 electrode exhibited good performance for the generation of weakly adsorbed hydroxyl radicals (HO?) during the OER in electrolyte-free water.  相似文献   

5.
Chemical preparation, crystal structure, and NMR spectroscopy of a new trans-2,5-dimethylpiperazinium monophosphate are given. This new compound crystallizes in the triclinic system, with the space group P-1 and the following parameters: a = 6.5033(3), b = 7.6942(4), c = 8.1473(5) Å, α = 114.997(3), β = 92.341(3), γ = 113.136(3), V = 329.14(3) Å3, Z = 1, and Dx = 1.565 g cm?3. The crystal structure has been determined and refined to R = 0.030 and R w(F 2) = 0.032 using 1558 independent reflections. The structure can be described as infinite [H2PO4] n n? chains with (C6H16N2)2+ organic cations anchored between adjacent polyanions to form columns of anions and cations running along the b axis. This compound has also been investigated by IR, thermal, and solid-state, 13C and 31P MAS NMR spectroscopies and Ab initio calculations.  相似文献   

6.
The crystal structure of bis(semicarbazido)copper(II) nitrate [Cu(NH2NHC(O)NH2)2](NO3)2 has been studied by X-ray diffraction. Monoclinic crystals, a = 6.835(2) Å, b = 7.733(2) Å, c = 10.320(3) Å, β = 105.701(3)°, V = 525.1(2) Å3, space group P21/c, Z = 2, d msd = 2.136 g/cm3, μ(MoK α) = 2.143 mm−1. The structure was solved with the program for automatic analysis of Patterson’s function and refined by full-matrix least squares in an anisotropic approximation for all non-hydrogen atoms using 753 independent reflections; R 1 = 0.0203. The square environment of the Cu atom is formed from the amino nitrogen atoms of the hydrazine fragments and the C=O oxygen atoms of the two semicarbazide bidentate molecules (Cu-N 1.928 Å, Cu-O 1.999 Å). The axial positions are occupied by the O atoms of the NO 3 outer-spheric anions (Cu-O 2.505 Å). In the structure, the complex cations and the NO 3 anions are linked into a framework by N-H...O type hydrogen bonds. Original Russian Text Copyright ? 2007 by G. V. Romanenko, Z. A. Savelieva, and S. V. Larionov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No. 2, pp. 370–373, March–April, 2007.  相似文献   

7.
Equilibrium geometric parameters, normal mode frequencies and intensities in IR spectra, atomization enthalpy, and relative energies of low-lying electronic states of scandium fluoride molecules (ScF, ScF2, and ScF3) are calculated by the coupled-cluster method (CCSD(T)) in triple-, quadruple, and quintuple-zeta basis sets with the subsequent extrapolation of the calculation results to the complete basis set limit. The ScF molecule is also studied by the CCSDT technique. The error in the approximate calculation of triple excitations in the CCSD(T) method does not exceed 0.002 Å for the equilibrium internuclear distance R e, 4 cm?1 for the vibrational frequency, and 0.2 kcal/mol for the dissociation energy of the molecule. In the ground electronic state \(\tilde X^2 \) A 1(C 2ν ) of ScF2 molecules, R e(Sc-F) = 1.827 Å and αe(F-Sc-F) = 124.2°; the energy barrier to bending (linearization) h = E min(D g8h ) ? E min(C) = 1652 cm?1. The relative energies of Ã2Δ g and \(\tilde B^2 \)Π g electronic states are 3522 cm?1 and 14633 cm?1 respectively. The bond distance in the ScF3 molecule (\(\tilde X^1 \) A1, D 3h ) is refined: R e(Sc-F) = 1.842 Å. The atomization enthalpies Δat H 298 0 of ScF k molecules are 139.9 kcal/mol, 289.0 kcal/mol, and 444.8 kcal/mol for k = 1, 2, 3 respectively.  相似文献   

8.
Powder and single crystal X-ray diffraction studies have been performed for anhydrous nitrate complexes Rb2[Pd(NO3)4] (I) and Cs2[Pd(NO3)4] (II). Crystal data for I: a = 7.843(1) Å, b = 7.970(1) Å, c = 9.725(1) Å; β = 100.39(1)°, V = 597.9(1) Å 3, space group P21/c, Z = 2, d calc = 2.918 g/cm3; for II: a = 10.309(2) Å, b = 10.426(2) Å, c = 11.839(2) Å; β = 108.17(3)°, V = 1209.0(4) Å3, space group P21/c, Z = 4, d calc = 3.408 g/cm3. The structures are formed by isolated [Pd(NO3)4]2? complex anions and alkali metal cations. The plane-square environment of the Pd atom is formed from the oxygen atoms of the monodentate nitrate groups. The geometrical characteristics of the complex anions are analyzed. Compound II has a short contact Pd...Cs 3.252 Å.  相似文献   

9.
A novel metal chalcogenide HgCd4S5 (1) was synthesized from solid-state reactions and structurally characterized. Compound 1 crystallizes in the space group C2221 of the orthorhombic system with four formula units in a cell: a = 12.5661(5) Å, b = 7.2551(5) Å, c = 10.7520(7) Å, V = 980.2(1) Å3, Cd4HgS5, M r = 810.49, D c = 5.492 g/cm3, S = 1.010, μ(MoK α) = 25.128 mm?1, F(000) = 1408, R = 0.0611 and wR = 0.1495. Compound 1 is characterized by a 3-D cadmium sulfide framework structure with the infinite mercury sulfide chains located in the cavities.  相似文献   

10.
The new phosphate Cs2Mn0.5Zr1.5(PO4)3 was synthesized for the first time and characterized by X-ray diffraction. Its crystal structure was refined in space group P213, Z = 4 at 25°C (a = 10.3163(1) Å, V = 1097.93(1) Å3), by the Rietveld method using the powder X-ray diffraction data. The structure is built of an octahedral-tetrahedral framework {[Mn0.5Zr1.5(PO4)3]2?}3∞ with cesium atoms being located in large cavities. The hydrolytic stability of the powdered phosphate containing 137Cs radionuclide was studied. The minimum achieved 137Cs leaching rate was 4 × 10?8 g/cm2 day.  相似文献   

11.
A novel one-dimensional chain complex [Cd(NITpPy)2(N(CN)2)2)] n (NITpPy = 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) has been synthesized and characterized structurally. It crystallizes in the triclinic space group P \(\bar 1\) with a = 7.1742(13), b = 9.4913(17), c = 13.208(2) Å, α = 71.020(2)°, β=87.308(2)°, γ = 70.503(2)°, V = 799.8(3) Å3, C28H32CdN12O4, Mr = 713.06, Z = 1, ρ c = 1.48 g/cm3, μ(MoK α) = 0.736 mm?1, F(000) = 364, R = 0.0275 and wR = 0.0605 for 2702 observed reflections with I > 2σ(I). The crystal structure consists of infinite chains of [Cd(NITpPy)2(N(CN)2)2)] units linked by dicyanamide anions [N(CN)2]?. Each Cd2+ ion is six-coordinated with the geometry of a distorted octahedron.  相似文献   

12.
Two cis-dioxomolybdenum(VI) complexes [MoO2L] (L: L 1, 2 and L: L 2, 3) in a phenol-based sterically encumbered N2O2 ligand environment have been synthesized, and their crystallographic characterizations are reported. The orange crystals of 2 are monoclinic, space group P21/a with unit cell dimensions as a=16.2407(17) Å, b=7.2857(8) Å, c=18.400(2) Å, β=98.002(9)°, Z=4, and d cal=1.486 g cm?3. The light orange crystals of 3, however, are orthorhombic, space group, Pbcn, with unit cell dimensions a=8.3110(12) Å, b=12.637(3) Å, c=34.673(5) Å, Z=4, and d cal=1.187 g cm?3. The structures were refined by a full-matrix least-squares procedure on F 2 to a final R=0.046 (0.055 for 3) using 4944 (3677) all independent data. In both the cases, the Mo atom exists in a distorted octahedral geometry defined by a N2O4 donor set, which features a cis-Mo(–O)2 and a trans-Mo(OPh)2 arrangement. Compound 2 undergoes a quasireversible one-electron reduction at ?1.3 V vs Ag/AgCl reference due to MoVIO2/MoVO2 electron transfer and thus providing a rare example of steric solution to the comproportionation–dimerization problem encountered frequently in the development of valid biomimetic models for the active sites of oxomolybdenum enzymes.  相似文献   

13.
The kinetics of 1,1-dimethylpropyl peroxy radicals recombination in polar solvents—water, methanol, and their mixtures—was studied by EPR spectroscopy in combination with the stopped-flow method, and the rate constants of this reaction were determined. Peroxyl radicals were generated by mixing solutions of Ce4+ sulfate and 1,1-dimethylpropyl hydroperoxide. The observed EPR signal of the peroxyl radical is a singlet with a g-factor of 2.015 ± 0.001, and a line width of ΔH = (1.36 ± 0.02) × 10?3 T for methanol and ΔH = (9.7 ± 0.2) × 10?4 T for water. The measured rate constants of (CH3)2C(O2·)CH2CH3 radical recombination at 298 K are 2kt = (3.9 ± 0.4) × 104 L mol?1 s?1 for water and 2kt = (5.2 ± 0.5) × 103 L mol?1 s?1 for methanol. A linear relationship between ln(2kt) and the Kirkwood function (ε?1)/(2ε + 1), where e is the dielectric constant of the medium, has been established, indicating an important role of nonspecific solvation in the recombination of tertiary peroxyl radicals.  相似文献   

14.

Background

Thiazolidinedione is a pentacyclic moiety having five membered unsaturated ring system composed with carbon, oxygen, nitrogen and sulfur molecules at 1 and 3 position of the thiazole ring and widely found throughout nature in various form. They favourably alter concentration of the hormones secreted by adipocytes, particularly adiponectin. They also increase total body fat and have mixed effects on circulating lipids. Thiazolidinedione nucleus is present in numerous biological moieties and has different pharmacological activities likes, e.g. antimalarial, antimicrobial, antimycobacterial, anticonvulsant, antiviral, anticancer, anti-inflammatory, antioxidant, anti-HIV (human immunodeficiency virus) and antituberculosis.

Results and discussion

The synthesized compounds were screened for their in vitro antimicrobial potential against Gram (positive and negative) bacterial and fungal strains by tube dilution technique. In this series, compound 10 exhibited significant antimicrobial activity against B. subtilis and S. aureus with MIC?=?4.2?×?10?2 µM/ml, compound 15 showed significant activity against K. pneumonia with MIC?=?2.60?×?10?2 µM/ml and compound 4 displayed potent antibacterial activity against E. coli with MIC?=?4.5?×?10?2 µM/ml. Compound 10 had most potent antifungal activity against C. albicans and A. niger with MIC?=?4.2?×?10?2 µM/ml. Compounds 12 and 15 were found as most active antidiabetic agents having IC50?=?27.63 μg/ml and 22.35 μg/ml, respectively, using DPPH assay. Antioxidant activity results indicated that compounds 3 and 9 displayed good antioxidant agent with IC50?=?29.04 μg/ml and 27.66 μg/ml respectively, using α amylase assay.

Conclusion

All the synthesized derivatives exhibited good antimicrobial, antidiabetic and antioxidant activities using specific methods then compared with mentioned standard drugs. Especially, compounds 3, 4, 9, 10, 12 and 15 displayed highest activity. Structure activity relationship demonstrated that presence of electron withdrawing group (o-NO2, p-Cl, p-Br) enhanced the antibacterial activity against E. coli as well as increased the antioxidant activity while the presence of electron releasing group (o/p-OCH3, 3,4,5-trimethoxy) enhanced the antibacterial activity against S. aureus, B. subtilis, S. typhi, K. pneumonia, C. albicans and A. niger as well as the antidiabetic activity.
  相似文献   

15.
The crystal structure of the compound OsSe2Br12 obtained by the reaction of OsBr4 with SeBr4 or Se in liquid bromine at 100°C was studied by X-ray powder diffraction. The structure of osmium selenobromide corresponds to a specific type: space group C2/m, a = 14.0464(2) Å, b = 11.05398(14) Å, c = 6.50340(9) Å, β = 112.2645(11)°, Z = 2; R B = 0.03946, R wp = 0.05403, χ2 = 4.261 for 479 reflections and 53 refinement parameters. The X-ray diffraction analysis confirmed the earlier assumption concerning the cation-anion structure of the compound representing a packing of nearly regular [OsBr6]2? octahedra as anionic complexes and deficient [:SeBr3]+ tetrahedra as cationic complexes in which the missing vertex is occupied by the lone electron pair of selenium.  相似文献   

16.
Conductivity of perovskite phosphate–substituted solid solutions of Ba4Ca2Nb2 x P x O11 (0.0 ≤ x ≤ 0.5) was studied as a function of temperature, partial pressure of oxygen and water vapors. It is proved that the studied systems are protonic conductors at the temperatures below 600°C in the atmosphere with elevated content of water vapors (pH2O = 1.92 × 10–2 atm). Introduction of the tetrahedral [PO4] group in the complex oxide matrix of Ba4Ca2Nb2O11 results in an increase in the oxygen–ionic (dry air, pH2O = 1.91 × 10–4 atm) and protonic conductivities (wet air, pH2O = 1.92 × 10–2 atm). Is it found that the doping causes a considerable increase in chemical stability of phases with respect to carbon dioxide.  相似文献   

17.
The temperature dependence of the heat capacity C p o of the [(Me3Si)7C60]2 fullerene complex was measured for the first time using precision adiabatic vacuum calorimetry over the temperature range 6.7–340 K and high-accuracy differential scanning calorimetry at 320–635 K. For the most part, the error in the C p o values was about ±0.5%. An irreversible endothermic effect caused by the splitting of the dimeric bond between fullerene fragments and the thermal decomposition of the complex was observed at 448–570 K. The thermodynamic characteristics of this transformation were calculated and analyzed. Multifractal analysis of the low-temperature (T < 50 K) heat capacity was performed, and conclusions were drawn concerning the character of the heterodynamicity of the structure. The experimental data obtained were used to calculate the standard thermodynamic functions C p o (T), H o (T) ? H o (0), S o (T) ? S o (0), and G o (T) ? H o (0) over the temperature range from T → 0 to 445 K and estimate the standard entropy of formation of the compound from simple substances at 298.15 K. The standard thermodynamic properties of [(Me3Si)7C60]2 are compared with those of the (C60)2 dimer, the [(η6-Ph2)2Cr]+[C60]?? fulleride, and the initial C60 fullerene.  相似文献   

18.
Bis-(3,3-dinitroazetidinyl)-oxamide ((DNAZ-CO)2) is an acyl derivative of 3,3-dinitroazetidine (DNAZ). It is prepared and its crystal structure is determined. The crystal is orthorhombic, Fdd2 space group, a = 13.136(14) Å, b = 19.48(3) Å, c = 10.326(14) Å, V = 2642 (6) Å3, Z = 8. A density functional theory (DFT) method of the Amsterdam Density Functional (ADF) package is used to calculate the geometry, frequencies, and properties. The optimized geometry, frontier orbital energy, and main atomic orbital percentage are obtained. The thermal behavior is studied under a non-isothermal condition by DSC and TG/DTG methods. The apparent activation energy (E a) and pre-exponential factor (A) of the exothermic decomposition reaction of (DNAZ-CO)2 are 164.10 kJmol?1 and 1013.38 s?1 respectively. The critical temperature of thermal explosion is 272.20°C. The values of ΔS , ΔH , and ΔG of this reaction are 6.44 Jmol?1·K?1, 163.76 kJmol?1 and 160.34 kJmol?1 respectively.  相似文献   

19.
The KPb2Cl5 and KPb2Br5 crystals are monoclinic (P21/c) with a microtwinned structure. X-ray analysis of chloride resulted in the parameters a = 8.854(2) Å, b = 7.927(2) Å, c = 12.485(3) Å; β = 90.05(3)°, dcalc = 4.78(1) g/cm3 (STOE STADI4, MoKα, 2θmax = 80°), R1 = 0.0702 for 4094 F ≥ 4 σ(F) reflections. For bromide, a = 9.256(2) Å, b = 8.365(2) Å, c = 13.025(3) Å; β = 90.00(3)°, dcalc = 5.62(1) g/cm3 (Bruker P4, MoKα, 2θmax = 70°), R1 = 0.0692 for 3076 F ≥ 4 (F) reflections.  相似文献   

20.
An investigation is conducted on enhancing lithium-ion intercalation and conduction performance of transparent organo tantalum oxide (TaO y C z ) films, by addition of lithium via a fast co-synthesis onto 40 Ω/□ flexible polyethylene terephthalate/indium tin oxide substrates at the short exposed durations of 33–34 s, using an atmospheric pressure plasma jet (APPJ) at various mixed concentrations of tantalum ethoxide [Ta(OC2H5)5] and lithium tert-butoxide [(CH3)3COLi] precursors. Transparent organo-lithiated tantalum oxide (Li x TaO y C z ) films expose noteworthy Li+ ion intercalation and conduction performance for 200 cycles of reversible Li+ ion intercalation and deintercalation in a 1 M LiClO4-propylene carbonate electrolyte, by switching measurements with a potential sweep from ?1.25 to 1.25 V at a scan rate of 50 mV/s and a potential step at ?1.25 and 1.25 V, even after being bent 360° around a 2.5-cm diameter rod for 1000 cycles. The Li+ ionic diffusion coefficient and conductivity of 6.2?×?10?10 cm2/s and 6.0?×?10?11 S/cm for TaO y C z films are greatly progressed of up to 9.6?×?10?10 cm2/s and 7.8?×?10?9 S/cm for Li x TaO y C z films by co-synthesis with an APPJ.  相似文献   

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