Two new Cu(II) linear trinuclear Schiff base complexes, [Cu3(L)2(CH3COO)2] (1) and [Cu3(L)2(CF3COO)2] (2), have been prepared using a symmetrical Schiff base ligand H2L [where H2L = N,N'-bis(2-hydroxyacetophenone)propylenediimine]. Both of the complexes have been characterized by elemental analyses, Fourier transform IR, UV/vis, and electron paramagnetic resonance spectroscopy. Single-crystal X-ray structures show that the adjacent Cu(II) ions are linked by double phenoxo bridges and a mu(2)-eta(1):eta(1) carboxylato bridge. In each complex, the central copper atom is located in an inversion center with distorted octahedral coordination geometry, while the terminal copper atoms have square-pyramidal geometry. Cryomagnetic susceptibility measurements over a wide range of temperature exhibit a distinct antiferromagnetic interaction of J = -36.5 and -72.3 cm(-1) for 1 and 2, respectively. Density functional theory calculations (B3LYP functional) and continuous-shape measurement (CShM) studies have been performed on the trinuclear unit to provide a qualitative theoretical interpretation of the antiferromagnetic behavior shown by the complexes. 相似文献
Mediterranean Journal of Mathematics - In this paper, we consider a nonlinear system of thermoviscoelastic with a nonlinear boundary damping and nonlinear source, in a bounded domain Ω, under... 相似文献
Three gemini cationic surfactants with different hydrophobic spacer chain lengths were synthesized and characterized. The inhibition effect of N,N′-bis(2-hydroxyethyl)-N,N′-dimethyl-N,N′-bis(2-(tetradecanoyloxy)ethyl)ethane-1,2-diaminium bromide (G-2); N,N′-bis(2-hydroxyethyl)-N,N′-dimethyl-N,N′-bis(2-(tetradecanoyloxy)ethyl) hexane-1,6-diaminium bromide (G-6); and N,N′-bis(2-hydroxyethyl)-N,N′-dimethyl-N,N′-bis (2-(tetradecanoyloxy) ethyl) dodecane-1,12-diaminium bromide (G-12) on the corrosion of carbon steel in 1.0 M HCl solution at 25–60 °C was studied by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy. The results show that the synthesized inhibitors are effective inhibitors even at very low concentration, and the adsorption on the carbon steel surface obeys the Langmuir adsorption isotherm. Potentiodynamic polarization curves reveal that the synthesized inhibitors behave as a mixed-type inhibitor. Adsorption of used inhibitors led to a reduction in the double layer capacitance and an increase in the charge transfer resistance. Thermodynamic parameters have been obtained by adsorption theory. Surface activity and corrosion inhibition relationship were discussed. The biodegradability of the synthesized surfactants showed their readily biodegradation in the open environment and were considered as environmentally friendly corrosion inhibitors.
A new lignan glucoside, officinalioside (1), was isolated from n-BuOH fraction of the aerial parts of Borago officinalis L., together with four known compounds: actinidioionoside (2), roseoside (3), crotalionoside C (4) and kaempferol 3-O-β-D-galactopyranoside (5). The structure of the new compound was established by means of spectroscopic and chemical analyses. Compounds 1 and 2 showed a moderate DPPH radical scavenging activity (IC50: 52.6 ± 1.70 and 41.3 ± 0.25 μM, respectively) comparable with that of the standard trolox (16.6 ± 2.2 μM) without any significant cytotoxicity towards human cell line A549 (IC50 > 100 μM). 相似文献
In this article, an optimal error estimate for parabolic variational inequalities is studied. Existence and uniqueness of the solution is provided by the introduction of a constructive algorithm. An optimally L∞-asymptotic behavior in uniform norm is proved using the semi-implicit time scheme combined with the finite element spatial approximation. The approach is based on the concept of subsolutions. 相似文献
Novel asymmetrically substituted azadithiolate compounds [Fe2(CO)4(kappa2-dppe){micro-SCH2N(R)CH2S}] (R=iPr, 1a; CH2CH2OCH3, 1b; CH2C6H5, 1c) have been synthesized by treatment of [Fe2(CO)6(micro-adt)] [adt=SCH2N(R)CH2S, with R=iPr, CH2CH2OCH3, CH2C6H5] with dppe (dppe=Ph2PCH2CH2PPh2) in refluxing toluene in the presence of Me3NO. 1a-c have been characterized by single-crystal X-ray diffraction analyses. The electrochemical investigation of 1a-c and of [Fe2(CO)4(kappa2-dppe)(micro-pdt)] (1d) [pdt=S(CH2)3S] in MeCN- and THF-[NBu4][PF6] has demonstrated that the electrochemical reduction of 1a-d gives rise to an Electron-transfer-catalyzed (ETC) isomerization to the symmetrical isomers 2a-d where the dppe ligand bridges the iron centers. Compounds 2a-d were characterized by IR and NMR spectroscopy, elemental analysis, and X-ray crystallography for 2a. 相似文献
Zirconyl chloride upon hydrolysis in water to form Zr(OH)+ has been found to react to form a fluorescent derivative with not only a ketose such as fructose but also a hexose such as glucose and the disaccharide sucrose. When reaction conditions such as a temperature of 99°C and a time of 60 min are used, detection limits below 1 μg/mL are possible. All three zirconyl–sugar derivatives show very similar absorbance and fluorescence spectra, indicating a common mechanism involving formation of an enediol which can be complexed with ZrOH+ is likely. Because the reactivity order is glucose < sucrose < fructose, the reaction can be made selective for fructose at a lower reaction temperature and time such as 60°C at 5 min. Because interference from ascorbic acid and caffeine is also avoided, the fluorescent determination of fructose in soft drink samples after simply a dilution step is possible. We have also employed this reaction for flow injection analysis (FIA) using a polystyrene–divinylbenzene-packed HPLC column as a mixing device. Using a 0.01 M HClO4 with 1% zirconyl chloride carrier, we obtained a linear calibration curve from 2 to 30 μg/mL with a correlation coefficient of 0.994. A detection limit less than 2 μg/mL was possible. A comparison of results for the FIA of soft drinks with the enzymatic method involving fructose-5-dehydrogenase confirmed the FIA method was quite specific for fructose. 相似文献
Rapidly quenched (Co95Fe5)1-xAlx ribbons are investigated by X‐ray diffraction, magnetization, and Mössbauer effect measurements. A single fcc phase is obtained for all ribbons x ? 10 at.%. The lattice constant increases linearly with x and is discussed in connection with magnetic moment. The influence of Al substitution on both magnetization and Fe‐atom hyperfine field (H) is studied. At 296 K, the magnetization decreases linearly while H drops nonlinearly as x increases. Al substitution leads to substantial differences in iron hyperfine fields in bcc and fcc systems. Fe moment is perturbed differently by Al substitution in fcc (Co95Fe5)1-xAlx and bcc Fe–Al systems. 相似文献
The strategic idea in this work was to increase pH values by employing natural alkali sources (i.e., HCO3− and CO32−) from four tested agro-ashes as an alternative to chemicals (i.e., lime or soda ash). The considerable proportion of carbonates and bicarbonates in the investigated ash products had remarkable features, making them viable resources. All ash materials showed a significant ability for Ca ion elimination at high initial Ca ion concentrations. A slight quantity of ash (10 g/L) was sufficient for usage on very hard water contents up to 3000 ppm. Finally, the tested agro-ash was free of cost. Furthermore, unlike other conventional precipitants, such as NaOH, Ca(OH)2, NaHCO3, Na2CO3, and CaO, they are cost effective and ecologically sustainable. There is no need to employ any additional chemicals or modify the agro-ash materials throughout the treatment process. The benefits of the manufactured ash were assessed using a SWOT analysis. 相似文献