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1.
《Inorganica chimica acta》1988,144(2):269-273
Lanthanoid nitrates react with 1,7,10,16-tetraoxa- 4,13-diaza-N,N′-dimethylcyclooctadecane, Me2(2,2), to give complexes with two different metal:ligand ratios, 1:1 (Ln = La, Ce, Tb) and 4:3 (Ln = Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho). The complexes were isolated from anhydrous solutions in acetonitrile and characterized by elemental analysis, X-ray diffraction, magnetic susceptibility measurements and vibrational analysis.The La and Ce 1:1 complexes are non-ionic and probably 12-coordinated, with the metal ion bound to the six donor atoms of the ligand and to three bidentate nitrate ions. The 4:3 complexes are ionic; they contain three bis(nitrato) complex cations [Ln(NO3)2·Me2(2,2)]+ and one hexakis(nitrato) anion [Ln(NO3)6]3−. Spectroscopic data, including luminescence spectra, point to the 1:1 Tb-complex as being a 4:3 complex with an additional outer-sphere coordinated molecule of ligand.In solution, the 1:1 complexes remain essentially non-ionic, although some dissociation cannot be ruled out, whereas the 4:3 complexes behave as 2:1 (of even 3:1) electrolytes.  相似文献   

2.
Electronic absorption and emission spectra, along with lifetime measurements and vibrational spectra, are used to investigate the interaction between nitrate and trivalent europium ions in dilute solutions in anhydrous and aqueous acetonitrile. Upon addition of increasing quantities of nitrate, the complexes [Eu(NO3)n](3?n)+, with n = 1–5, form quantitatively in anhydrous acetonitrile. In solution, the pentanitrato species is not further solvated and its spectroscopic properties are similar to those of solid samples, indicating a similar structure with five bidentate nitrates bonded to the 10-coordinate Eu(III) ion. The lifetimes of the 5D0 level are 1.35(5) and 1.25(5) ms for Eu(NO3)3 and (Me4N)2Eu(NO3)5 0.05 M in CH3CN. The quantum yield of Eu(NO3)3 in CH3CN is 27.4%.The addition of small quantities of water to Eu(NO3)3 solutions does not result in the dissociation of the nitrate ions, provided Rw = [H2O]t/[Eu3+]t is smaller than 8; the apparent equilibrium rations for [Eu(NO3)3(H2O)n] are K3 = 40 ± 15 M?1 and K4 = 9 ± 3 M?1; K1 and K2 are too large to be determined. The formation of nitrato complexes is studied in mixtures containing increasing amounts of water and nitrate. Deconvolution of the different components of the 5D07F0 transition allows a semi-quantitative estimate of the relative concentration of the nitrato complexes. The total number of coordinated nitrate ions per europium ion can be determined on the basis of fluorescence lifetime measurements. The apparent equilibrium ratios for the formation of the mono- and dinitrato species amount to K1 = 23 ± 3, 15 ± 5 and 5 ± 1 for Rw = 44, 94 and 304, respectively, and to K2 = 17 ± 8 for Rw = 44 and 94.  相似文献   

3.
In this work a new highly fluorescent N,N‐dimethyl benzylamine–palladium(II) yu complex was synthesized by the reaction of [Pd2{(C,N–C6H4CH2N(CH3)2}2(μ‐OAc)]2] with curcumin. The structure of the synthesized complex was characterized using Fourier transform infra‐red (FT‐IR) spectroscopy, 1H nuclear magnetic resonance spectroscopy, and elemental analysis. Fluorescence quantum yield (ΦF) values of the synthesized complex in dimethyl sulfoxide (DMSO), acetonitrile, ethanol, and methanol were 0.160, 0.104, 0.068, and 0.061, respectively. The fluorescence signal of the complex in the organic solvents was very sensitive to the water content of the organic solvent. The quenching effect of water was used to determine trace amounts of water in the heteroatom‐containing organic solvents (ethanol, methanol, acetonitrile) and redox‐active solvents (DMSO). The linear ranges for determination of water (v/v %) in ethanol, DMSO and acetonitrile were found to be 0.03–14.5, 0.08–13.8, and 0.07–18.8, respectively. Two linear ranges were found for determination of water (v/v %) in methanol (0.1–1.2 and 4.7–25.0). Detection limit (DL) values were calculated to be 0.001, 0.05, 0.004, and 0.01 (v/v %) in ethanol, methanol, acetonitrile, and DMSO, respectively. The proposed method overcomes the problems of the standard Karl Fischer method for determination of water in DMSO. In addition, it gave the best DL value for determination of water in ethanol compared with all published papers to date.  相似文献   

4.
Fluorescence study of the complexation between uranyl salophen (L) and some common anions in acetonitrile–water (90:10, v/v) solution showed a tendency of L toward acetate ion (AcO?). The fluorescence enhancement of L is attributed to a 1:1 complex formation between L and acetate ion which was utilized as the basis for the selective detection of AcO?. The association constant of the 1:1 complex formation of L–AcO? was calculated as 6.60 × 106. The linear response range of the fluorescent chemosensor covers a AcO? concentration range of 1.6 × 10?7 to 2.5 × 10?5 mol/L, with a detection limit of 2.5 × 10?8 mol/L. L showed a selective and sensitive fluorescence enhancement response toward acetate ion over I3?, NO3?, CN?, CO32?, Br?, Cl?, F?, H2PO4? and SO42?, which was attributed to the higher stability of inorganic complex between acetate and L. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

5.
A rapid HPLC method with UV absorbance detection at 333 nm for the measurement of nitrite and nitrate in ultrafiltrate samples of human plasma is described. The method is based on hydrochloric acid-catalyzed conversion of nitrite by N-acetyl-l-cysteine to S-nitroso-N-acetyl-l-cysteine and isocratic elution using 10 mM NaH2PO4 in acetonitrile–water, pH 2.0 (15:85, v/v). The limit of detection of the method is 50 nM nitrite. The method was validated by gas chromatography–mass spectrometry.  相似文献   

6.
We present 42 dual-isotope nitrate analyses of fresh water samples collected in the St. Lawrence River between June 2006 and July 2008. Measured δ15N–NO3 ? and δ18O–NO3 ? values correlate negatively, while δ18O–NO3 ? displays no negative correlation with nitrate concentration. This suggests that nitrate uptake and/or elimination by denitrification is not the main driver of observed variations in nitrate concentration and isotopic signature in the St. Lawrence River. In addition, δ18O–NO3 ? is negatively correlated with the seasonally variable δ18O of ambient water, indicating that the variation in the isotopic signature of nitrate is barely modulated by in-stream nitrate regeneration (nitrification). It rather is constrained by along-river changes in the external sources of nitrate. Given the distinct nitrogen (N) and oxygen (O) isotopic signature of atmospheric nitrate, we argue that observed seasonal variations of δ15N–NO3 ? and δ18O–NO3 ? in the St. Lawrence River are due to variable contributions of snowmelt-derived water. Based on a N and O isotope mass balance, we show that total nitrate loading in the St. Lawrence River is dominated by a N input from the Great Lakes (47 ± 28 %) and from nitrate regeneration of both internal and external N (48 ± 22 %). While temporal nitrate N and O isotope dynamics in the St. Lawrence River are mainly influenced by the atmospheric N input fluctuations, with an increase in atmospheric loading during spring, atmospheric N plays overall a rather insignificant role with regards to the N budget (5 ± 4 %).  相似文献   

7.
The objective of this study was to assess the impacts of land use changes and irrigation water resource on the nitrate contamination in shallow groundwater. 394 water samples were sampled from the same irrigation wells during a period of five years (from 2002 to 2007) in Huantai County in the North China Plain. NO3-N concentration in irrigation wells was measured. Geostatistical method combined with GIS technique was used to analyze the spatio-temporal distribution of groundwater NO3-N concentrations in Huantai County. Land use type and irrigation water resource were combined with the variation of NO3-N concentrations by statistical approach to investigate the relationship between them. The distribution map showed that the percentages of area increased by 13.06%, 14.37%, 12.23% and 3.85% for that had nitrate concentrations of 10–15, 15–20, 20–30 mg L?1 and greater than 30 mg L?1 for shallow groundwater, respectively, while decreased by 28.87% and 14.63% for 0–5 and 5–10 mg L?1. In the well-irrigated field, the NO3-N concentrations in shallow groundwater had increased for vegetables, wheat–vegetables and wheat–maize rotations. In contrast, fast-growing tree system could act as a buffer to retain shallow groundwater nitrate content which resulted in reduced NO3-N concentrations. Under the same land use condition, irrigation with sewage, or well and sewage by turns would both enormously add nitrate to groundwater.  相似文献   

8.
Biodegradation and mineralization of petroleum, added at 1% (v/v) to freshly collected sea water, were measured using gas–liquid chromatographic, residual weight, and CO2-evolution techniques. Only 3% of the added petroleum was biodegraded and 1% was mineralized in unamended sea water after 18 days of incubation. Added individually, nitrate (10?2 M) or phosphate (3.5 × 10?4 M) supplements caused little improvement, but when added in combination, they increased petroleum biodegradation and mineralization to 70% and 42%, respectively. Attempts to clean up oil spills with the aid of microorganisms should take into consideration the nutritional deficiencies of sea water.  相似文献   

9.
The potential nitrogen sources for the primary production in the intertidal area are nitrogen compounds obtained from mineralization in the sediment and the water column, nitrogen fixation, outflow from rivers and groundwater seeping from the mainland. The available inorganic nitrogen in the adjacent coastal waters decreases from 50–80 μmol NO3 -/l and 6–15 μmol NH4 +/l in early spring to ca one tenth during the growing season. In the sediment of the tidal flats available ammonia and nitrate vary between 50 and 100 μmol/1 pw. In the salt marsh available ammonia increases from 200–300 nmol NH4 +/g fwt to approximately double the amount, and the available nitrate varies from 100–300 nmol NO3 -/g fwt (250–750 μmol NO3 -/l pw) to ca one third during the growing season. The exchange of NH4 +, NO2 - and NO3 - across the sediment water interface has been estimated during tidal cycles under light and dark conditions on the tidal flats. The flux of nitrogen was dependent on the flora and fauna as well as the time of the year. The tidal activity, frequency and length of inundation are considered the driving force in a two-way process between salt marshes and adjacent coastal waters. The role of marsh sediment, tidal water and sediments of the tidal flats as sites of accumulation, consumption and remineralization of organic matter is emphasized. The possible exchange of ammonia and nitrate between the salt marsh and the different compartments of the tidal water is discussed.  相似文献   

10.
Water hyacinth was cultured in a flow-through system with constant nutrient availability and 1.4 mg 1?1 NO3-N as the nitrogen source. Tissue nitrate content ranged from 0.05 to 0.21% of dry wt. and accounted for 1.7–6.6% of the total nitrogen in the plant. Highest tissue nitrate levels occurred during the winter period of low plant growth rates and decreased as dry matter productivity increased. In the winter, the nitrate content of water hyacinth exceeded levels considered safe for conventional forage crops used for livestock feed.  相似文献   

11.
Two new salts based on heterocyclic organic cations and uranyl triacetate anion were obtained via reaction of zinc uranyl acetate with 2-substituted imidazoles in presence of an excess of acetic acid. Uranyl triacetate anion in [2-MeImH]+ [UO2(CH3COO)3] and [2-PhImH]+ [UO2(CH3COO)3] H2O has an expected bipyramidal structure with linear uranyl group and three acetate groups laying in equatorial plane. [2-MeImH]+ [UO2(CH3COO)3] structure analysis reveals H-bonded 1D chains connected through N-H···O hydrogen bonds. 2-phenylimidazolium in [2-PhImH]+ [UO2(CH3COO)3] H2O demonstrate planar geometry without any rotation of its rings, which was not registered before. H-bonds and π-π interactions of phenyl groups in this system lead to complicate 2D “sandwich” layer formation. The main features of IR- and luminescence spectrum of both compounds are also discussed.  相似文献   

12.
We developed a new chromogenic and fluorescent ‘turn‐on’ chemodosimeter 1 based on a F‐triggered cascade reaction. This system displayed significant changes in UV/vis absorption and fluorescence emission intensities selectively for F over other anions in a mixture of CH3CN/H2O (95 : 5, v/v) and in acetonitrile. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

13.
Campylobacter sputorum subsp. bubulus contained hydrogenase activity after growth with lactate and nitrate and after growth with hydrogen and nitrate. After growth with hydrogen and nitrate a molar growth yield (g dry cells/mol hydrogen) of 5.6 was measured. Hydrogenase and nitrate reductase were membrane-bound enzymes. In cells with high hydrogenase activity the H+/O, H+/NO inf2 sup- and H+/NO inf3 sup- values with hydrogen as the electron donor were 3.74, 2.61 and 4.36 respectively. In cells with low hydrogenase activity these values were 2.33,-0.86 and 1.31 respectively. These values and the stoichiometry of respiration-driven proton translocation (H+/2e=2) led to the conclusion that hydrogenase is located at the periplasmic side of the cytoplasmic membrane. In cells with low lactate dehydrogenase activity or low hydrogenase activity the reduction of nitrate to nitrite could be separated from the reduction of nitrite to ammonia. Positive H+/NO inf3 sup- values (between 0.9 and 1.7) with lactate or hydrogen as the electron donor were measured in these cells whereas H+/NO inf2 sup- values were negative. From this result it was concluded that nitrate reductase is located at the cytoplasmic face of the cytoplasmic membrane. The results explain the previous observation that molar growth yields with nitrate were somewhat higher than those with nitrite.  相似文献   

14.
The mechanisms of cytotoxic effect of uranyl nitrate were studied. It was shown that uranyl nitrate induced HEp-2 cell death, mainly by necrotic way. In the experiments in vitro, uranyl nitrate caused an appearance of 8-oxoguanine in DNA, indicating the induction of oxidative stress. The experiments with isolated rat liver mitochondria revealed that 1 mM uranyl nitrate decreased the respiration rates of mitochondria in state 3 and DNP-induced respiration. At the same time, uranyl nitrate had no influence on the opening of the mitochondrial permeability transition pore and decreased the rate of formation of H2O2 by mitochondria. Possible molecular mechanisms of uranyl-induced necrosis are discussed.  相似文献   

15.
Low temperature 31P and 15N NMR spectroscopy was used to investigate the species forming in the organic layer following the extraction of uranium from nitric acid solutions with di-2-ethylhexyl phosphoric acid. It was found that uranium is extracted from neutral solutions as the 1:2 complex UO2A2 regardless of what anion is present. For dilute nitric acid solutions, the uranium is extracted both as associated and mixed nitrato species. As the nitric acid concentration of the aqueous layer increases, the mixed nitrato complex, UO2(NO3)A·HA, becomes predominant.  相似文献   

16.
Low temperature 31P and 15N NMR spectroscopy was used to investigate the species forming in the organic layer following the extraction of uranium from nitric acid solutions with di-2-ethylhexyl phosphoric acid. It was found that uranium is extracted from neutral solutions as the 1:2 complex UO2A2 regardless of what anion is present. For dilute nitric acid solutions, the uranium is extracted both as associated and mixed nitrato species. As the nitric acid concentration of the aqueous layer increases, the mixed nitrato complex, UO2(NO3)A·HA, becomes predominant.  相似文献   

17.
A colorimetric and ratiometric fluorescent sulfite probe, the levulinate of 4‐hydroxynaphthalimide, was successfully synthesized from 4‐hydroxy‐naphthalimide and levulinic acid. Through sulfite‐mediated intramolecular cleavage, the probe was converted into 4‐hydroxynaphthalimide, which when excited at 450 nm, displayed a large Stokes shift due to the intramolecular charge transfer process. The probe exhibited high selectivity and sensitivity towards sulfite over other typical anionic species (F, Cl, Br, I, HPO42–, SO42–, NO3, AcO, ClO4, HCO3) in HEPES‐buffered solution (25 mm , pH 7.4, 50% acetonitrile, v/v). Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

18.
Nanoparticles with the nominal composition Ca0.8Ba0.2Ti03:Pr3+ were prepared using the sol–gel process. Barium nitrate, 4‐hydrated calcium nitrate and praseodymium oxide were used as raw materials. The structural evolution and decomposition processes of the precursors were investigated by powder X‐ray diffraction, differential thermal analysis and thermogravimetric analysis. Crystalline Ca0.8Ba0.2Ti03:Pr3+ could be obtained at 700°C. The photoluminescence properties of the samples were investigated using excitation and emission spectra. Ca0.8Ba0.2Ti03:Pr3+ nanoparticles showed strong red emission, which could be assigned to the typical 1D23H4 transition of Pr3+. Furthermore, the study found that sintering temperature and the introduction of Ba2+ influence the decay time of persistent luminescence. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

19.
Diurnal variations in relative water content (RWC), nitrate reductase (NR) and proline content (PC) were studied at 3 h intervals during a 24 h cycle in the flag leaf of wheat (Triticum vulgare, v. Kalyansona) grown under stressed and non-stressed conditions. RWC was lower in stressed plants than in non-stressed ones throughout the 24 h period. Although it was lowest at 12 h, it recovered by 15 h. Non-stressed plants maintained higher NR activity compared to those under stress. The enzyme activity during night was about the same as during day time in both types of plants. Compared to non-stressed plants, stressed ones had lower NO3? content. Proline accumulation occurred under stress conditions and had a maximum at 12–15 h. Non-stressed plants exhibited higher PC during night than day time. Changes in temperature and relative humidity were noted during the period and their influence on RWC, NR and proline was discussed.  相似文献   

20.
-Chymotrypsin was covalently modified with cellobiose by chemical means. After adsorption on to a porous polyamide support, both the native and the glycosylated immobilized derivatives were used to synthesize a kyotorphin derivative (N-benzoyl-l-tyrosyl-l-argininamide) in acetonitrile/water. Glycosylated chymotrypsin gave a 125% increase in product formation (750 nmol mg–1 catalyst in 3 h) at 60% (v/v) acetonitrile/water. Maximal protective effect of this glycosylation process was at 70% (v/v) acetonitrile/water, at which concentration the half-life of the glycosylated enzyme was 20-times longer than that of the native form (52 min and 2.8 min, respectively).  相似文献   

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