共查询到20条相似文献,搜索用时 31 毫秒
1.
Glen B. Deacon Peter W. Felder Peter C. Junk Timothy J. Ness 《Inorganica chimica acta》2005,358(14):4389-4393
An X-ray crystal structure has shown that the previously reported bis(p-hydroxytetrafluorophenyl)mercury crystallises as a monohydrate [Hg(C6F4OH-p)2(OH2)] exhibiting rare coordination of water to a diorganomercurial. The stereochemistry of the three-coordinate mercury is T-shaped with the water coordinated perpendicular to the near linear C-Hg-C unit. The molecules are linked in chains by hydrogen bonding between the hydroxy groups, and the chains into layers by hydrogen bonding between the water oxygen and an OH group. Thermogravimetric analysis shows two water molecules are eliminated together, both the coordinated water and one formed through condensation of the linked -OH groups. In [Hg(p-MeOC6H4)(O2CC6F4OMe-p)], molecules with a near linear strongly bonded C-Hg-O arrangement are observed. These are linked into a linear polymer through Hg-O (carboxylate) bridges giving alternate four-membered and eight-membered rings giving mercury overall square planar stereochemistry. 相似文献
2.
Recent updates on Magnetic Nano-Particles (MNPs) based separation of nucleic acids have received more attention due to their easy manipulation, simplicity, ease of automation and cost-effectiveness. It has been indicated that DNA molecules absorb on solid surfaces via hydrogen-bonding, and hydrophobic and electrostatic interactions. These properties highly depend on the surface condition of the solid support. Therefore, surface modification of MNPs may enhance their functionality and specification. In the present study, we functionalized Fe3O4 nano-particle surface utilizing SiO2 and TiO2 layer as Fe3O4/SiO2 and Fe3O4/SiO2/TiO2 and then compare their functionality in the adsorption of plasmid DNA molecules with the naked Fe3O4 nano-particles. The result obtained showed that the purity and amount of DNA extracted by Fe3O4 coated by SiO2 or SiO2/TiO2 were higher than the naked Fe3O4 nano-particles. Furthermore, we obtained pH 8 and 1.5 M NaCl as an optimal condition for desorption of DNA from MNPs. The result further showed that, 0.2 mg nano-particle and 10 min at 55 °C are the optimal conditions for DNA desorption from nano-particles. In conclusion, we recommended Fe3O4/SiO2/TiO2 as a new MNP for separation of DNA molecules from biological sources. 相似文献
3.
Salvatore V. Pizzo John J. Pasqua 《Biochimica et Biophysica Acta (BBA)/General Subjects》1982,718(2):177-184
The clearance of human fibrinogen fragments D1, D2, D3 and fibrin fragment D1 dimer were studied in the mouse model. Clearance of these fragments is a complex process involving clearance from blood into three other compartments. The overall clearance of fragment D1 and its dimer were essentially identical. Fragments D2 and D3 cleared at a progressively slower rate. Competition studies were performed between 125I-labeled fragment D1 and large molar excesses of unlabelled human fragments D1, D2, D3, D1 dimer, fragment E, fibrinogen, macroalbumin, mannan and asialooroscomucoid. Of these ligands only the fragment D variants competed for the clearance of 125I-labeled fragment D1. Cross-competition was observed when 125I-labeled fragment D1 dimer was cleared in the presence of large molar excesses of fragment D1. Autopsies demonstrated that injected fragments D1, D2, D3 and D1 dimer cleared primarily in liver and kidneys. In some clearance studies, livers were perfused with tissue culture fluid, subjected to light microscopic autoradiography, and silver grain counts performed to localize cleared fragment D1. These experiments indicated that 80% of the liver uptake was in hepatocytes. However, when silver grain counts were normalized for the number of parenchymal and nonparenchymal cells, the distribution of silver grains was essentially identical (1.8 and 1.6 grains per cell, respectively). It is concluded that fragments D1, D2, D3 and D1 dimer are recognized by a similar clearance pathway. Since neither fibrinogen nor fragment E competed for the clearance of fragment D1, it is suggested that determinants present in the fragment D domain become exposed after plasmin attack on fibrinogen and are responsible for clearance. 相似文献
4.
Metal-sulfur complex fragments, to which small molecules like N2, N2H2, N2H4, NH3, or CO can bind, are desirable model compounds concerning enzymatic N2 fixation.This paper reports on the effects of the phosphane co-ligand on formation and reactivity of [Ru(L)(PR3)(`N2Me2S2')] [`N2Me2S2'2−=1,2-ethanediamine-N,N′-dimethyl-N,N′-bis(2-benzenethiolate)(2−)] complexes with nitrogenase relevant ligands, especially N2, N2H4, NH3, and CO.Treatment of [Ru(NCCH3)4Cl2] with Li2`N2Me2S2', excessive LiOMe, bulky PPh3 or PCy3, respectively, led to the formation of two series of [Ru(L)(PR3)(`N2Me2S2')] complexes [for R=Ph: 1b, 1c (L=NCCH3), 6b (L=N2H4), 7b (L=N2), 8b1-3 (L=CO), 9b (L=NH3); for R=Cy: 1a (L=NCCH3), 6a (L=N2H4), 7a (L=N2), 8a (L=CO), 9a (L=NH3)]. While the use of PPh3 (θ=145°) yielded cis,trans and cis,cis isomers of [Ru(NCCH3)(PPh3)(`N2Me2S2')] (1b, 1c), no isomer formation was observed with the bulkier phosphane PCy3 (θ=170°). Sterically less demanding phosphanes (θ=118-132°) afforded bisphosphane complexes [Ru(PR3)2(`N2Me2S2')] [2d (R=Me), 2e (R=Et), 2f (R=nPr), and 2g (R=nBu)], which were practically inert and could only be converted in two cases and under drastic reaction conditions into the CO complexes [Ru(CO)(PR3)(`N2Me2S2')] [4e (R=Et), 4f (R=nPr)]. The chelating bidentate phosphane dppe (bisdiphenylphosphanoethane) yielded exclusively the mononuclear complex [Ru(dppe)(`N2Me2S2')] (3). 相似文献
5.
The title compounds were made by reacting bis(diphenylphosphino)methane (dppm) with reduced solutions of OsCl64? and Ru2OCl104?. The crystal and molecular structures of these compounds have been determined form three-dimensional X-ray study. The cis-isomers crystallize with one CHCl3 per molecule of the complex. All three compounds crystallize in the monoclinic space group P21/n with unit cell dimensions as follows: Cis-OsCl2(dppm)2·CHCl3: a = 13.415(4) Å, b = 22.859(4) Å, c = 16.693(3) Å, β = 105.77(3)°, V = 4926(3) Å3, Z = 4. cis-RuCl2(dppm)2·CHCl3: a = 13.442(3) Å, b = 22.833(7) Å, c = 16.750(4) Å, β = 105.53(2)°, V = 4953(3) Å3, Z = 4. trans-RuCl2(dppm)2: a = 11.368(7) Å, b = 10.656(6) Å, c = 18.832(12) Å; β = 103.90(6)°, V = 2213(7) Å3; Z = 2. The structures were refined to R = 0.044 (Rw = 0.055) for cis-OsCl2(dppm)2·CHCl3; R = 0.065 (Rw = 0.079) for cis-RuCl2(dppm)2·CHCl3 and R = 0.028 (Rw = 0.038) for trans-RuCl2(dppm)2. The complexes are six coordinate with stable four-membered chelate rings. The PMP angle in the chelate rings is ca. 71° in each case. 相似文献
6.
C4 photosynthesis in a single C3 cell is theoretically inefficient but may ameliorate internal CO2 diffusion limitations of C3 leaves 总被引:2,自引:1,他引:1
S. VON CAEMMERER 《Plant, cell & environment》2003,26(8):1191-1197
Attempts are being made to introduce C4 photosynthetic characteristics into C3 crop plants by genetic manipulation. This research has focused on engineering single‐celled C4‐type CO2 concentrating mechanisms into C3 plants such as rice. Herein the pros and cons of such approaches are discussed with a focus on CO2 diffusion, utilizing a mathematical model of single‐cell C4 photosynthesis. It is shown that a high bundle sheath resistance to CO2 diffusion is an essential feature of energy‐efficient C4 photosynthesis. The large chloroplast surface area appressed to the intercellular airspace in C3 leaves generates low internal resistance to CO2 diffusion, thereby limiting the energy efficiency of a single‐cell C4 concentrating mechanism, which relies on concentrating CO2 within chloroplasts of C3 leaves. Nevertheless the model demonstrates that the drop in CO2 partial pressure, pCO2, that exists between intercellular airspace and chloroplasts in C3 leaves at high photosynthetic rates, can be reversed under high irradiance when energy is not limiting. The model shows that this is particularly effective at lower intercellular pCO2. Such a system may therefore be of benefit in water‐limited conditions when stomata are closed and low intercellular pCO2 increases photorespiration. 相似文献
7.
Jeramie J. Adams 《Inorganica chimica acta》2009,362(6):2056-640
Electron poor cationic complexes [(CF3PCP)Pt(L)]+ (where L = CO, NC5F5, or acetone) react with H2O in polar solvents via selective hydrolysis of a single P-CF3 substituent to afford the spectroscopically-characterized phosphinoyl-bridged complex {k3-P,C,P,k1-O-(CF3)2PCH2C6H3CH2P(CF3)O}2Pt2 (1) in good yield. X-ray diffraction confirms the presence of a six-member Pt-P-O-Pt-P-O ring in a chair conformation. The presumed intermediate aqua complex, (CF3PCP)Pt(H2O)+, is stable in dichloromethane, but when dissolved in more polar solvents readily converts to 1. 相似文献
8.
A novel organic-inorganic hybrid pentaborate [Ni(C4H10N2)(C2H8N2)2][B5O6(OH)4]2 has been synthesized by hydrothermal reaction and characterized by FT-IR, Raman spectroscopy, elemental analyses and DTA-TGA. Its crystal structure was determined from single crystal X-ray diffraction. The structure consists of isolated polyborate anion [B5O6(OH)4]− and nickel complex cation of [Ni(C4H10N2)(C2H8N2)2]2+, in which the two kinds of ligands come from the decomposition of triethylenetriamine material. The [B5O6(OH)4]− units are connected to one another through hydrogen bonds, forming a three-dimensional framework with large channel along the a and c axes, in which the templating [Ni(C4H10N2)(C2H8N2)2]2+ cations are located. The assignments of the record FT-IR absorption frequencies and Raman shifts were given. 相似文献
9.
Dependence of the Post-Illumination Burst of CO2 on Temperature, Light, CO2 , and O2 Concentration in Wheat (Triticum aestivum) 总被引:3,自引:0,他引:3
The effect of environmental factors on the post-illumination burst of CO2 (PIB) and O2 inhibition of apparent photosynthesis (APS) in wheat (Triticum aestivum L.) was studied in an open gas exchange system utilizing the mathematics of non-steady-state systems. Two components of inhibition by O2 are suggested: one is caused by photorespiration as measured from the maximum rate of the PIB, and the second is direct inhibition as taken as APS2%O2— (APSx%O2+ PIBx%O2) where X is the oxygen concentration. A primary PIB which occurred from 16–28 s after the darkening of the foliage was attributed to photorespiration. No primary PIB was observed at 2% O2. At a CO2 concentration of 100 μ/1 in the atmosphere (about 2.5 μM based on leaf intercellular concentration) and at 30°C and 145 nE/cm2 nE/cm2·s, APS decreased curve-linearly with increasing O2 and reached an O2 compensation point of 560 μM (48% by volume), above which there was a net loss of CO2 in the light. The PIB increased with increasing O2 and became saturated at about 500 μM O2 but decreased above 900 μM O2. Direct inhibition of photosynthesis by O2 increased with increasing O2 concentration. Decreasing CO2 concentration had an effect on the magnitude of the PIB similar to that of increasing O2. At 30°C and 21% O2, the PIB increased with decreasing CO2 down to the CO2 compensation point (I) of 1.4 μM (47 μM/l). Below Γ, both PIB and CO2 evolution into the air in the light (at 21% O2) increased and then decreased at CO2 below 0.8 μM. The ratio of the PIB to APS2% o O2 increased linearly with increasing O2/CO2 ratio where O2 was held constant at 21% and CO2 was varied from 1.4 to 8.5 μM, while direct inhibition of photosynthesis expressed as a proportion of APS2%O2 remained constant over this range. At low CO2 concentration photorespiration as estimated by the PIB is the major part of O2 photosynthesis, while at atmospheric CO2 levels, direct inhibition is the major component. The PIB and APS at 2% and 21% O2 increased hyperbolically with increasing irradiance and all became light-saturated at about 65 nE/cm2 s. The percentage total O2 inhibition of photosynthesis remained constant with increasing irradiance as did the relative contribution of direct O2 inhibition or photorespiration (PIB) to total O2 inhibition. The PIB and APS at 21% O2 had similar temperature optima of 30°C when experimental conditions were adjusted to provide a constant internal O2/CO2 solubility ratio at varying temperatures. However, with a constant external CO2 concentration, the temperature optimum for the PIB shifted upward to 35°C while that for APS at 21% O2 remained at 30°C, which may be due to an increased O2/CO2 concentration in the leaf with increasing temperature. 相似文献
10.
A new CoII/CoIII hexanuclear complex, [Co4IICo2III(dea)2(Hdea)4)(piv)4](ClO4)2·H2O 1, has been obtained by reacting cobalt(II) perchlorate, diethanolamine, and pivalic acid (H2dea = diethanolamine and piv = pivalato anion). The cobalt ions are held together by four μ3 and four μ2 alkoxo bridges as well as by four syn-syn carboxylato groups. The hexanuclear motif contains four Co(II) and two Co(III) ions. The {CoII4CoIII2(μ2-O)4(μ3-O)4} core can be described as a four face-sharing monovacant and bivacant distorted heterocubane units. The cobalt(III) ions are hexacoordinated. Two of the cobalt(II) are hexacoordinated, while the two others are pentacoordinated with a bipyramidal stereochemistry. The magnetic properties of 1 have been investigated in the temperature range 1.9-300 K. Compound 1 exhibits an overall antiferromagnetic behaviour with a ground singlet spin state. 相似文献
11.
Anders Kussak Barbro Andersson Kurt Andersson 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1995,672(2)
A method for the determination of aflatoxins B1, B2, G1, G2, M1 and Q1 in human urine has been developed. The 10-ml urine samples were automatically cleaned up on immunoaffinity columns and analysed by high-performance liquid chromatography (HPLC), including post-column derivatization with bromine and fluorescence detection. Average aflatoxin recoveries were: B1 103%, B2 106%, G1 98% and G2 96% in the range 6.8–73 pg/ml of urine and M1 103% and Q1 100% in the range 18–97 pg/ml of urine. The relative standard deviations were all between 1% and 21%. The determination limits of aflatoxins in urine were 6.8 pg/ml for B1, B2, G1 and G2 and 18 pg/ml for M1 and Q1. 相似文献
12.
O. Anjaneyulu 《Inorganica chimica acta》2010,363(12):2990-2995
Preferential formation and X-ray structures of tris(4-hydroxypyridinium) nitrato complexes [M(4-O-C6H4NH)3(NO3)2(H2O)2][NO3] {M = La, Ce, Pr, Nd, Eu, Gd} in the simple reaction of 4-hydroxypyridine with the respective nitrates is described. All these compounds are isostructural and crystallize in the space group P212121. There are, however, minor differences in the hydrogen bonding features. The central metal ion in all these complexes has a coordination number of nine and the geometry may be described as tricapped trigonal prism. The neodinium complex has a chirality opposite to that of the rest of the structures. TGA data are also consistent with the solid state structures of these compounds. 相似文献
13.
14.
The advantages and disadvantages of using the Xα scattered-wave molecular orbital method with quasi-relativistic corrections for the calculation of the electronic structure of organo-f-element compounds is discussed. Application of the method in organouranium chemistry is discussed via comparative calculations on UCl4, (η5-C5H5)4U, and (η5-C5H5)2UCl2. It is found that the η5-C5H5? ligand is a better donor to U than is Cl? and that the valence orbitals of (η5-C5H5)2UCl2 are energetically closer to those of (η5-C5H5)4U than UCl4. The calculational results are in excellent accord with experimental photoelectron spectroscopic studies. 相似文献
15.
Immediate export in leaves of C3‐C4 intermediates were compared with their C3 and C4 relatives within the Panicum and Flaveria genera. At 35 Pa CO2, photosynthesis and export were highest in C4 species in each genera. Within the Panicum, photosynthesis and export in ‘type I’ C3‐C4 intermediates were greater than those in C3 species. However, ‘type I’ C3‐C4 intermediates exported a similar proportion of newly fixed 14C as did C4 species. Within the Flaveria, ‘type II’ C3‐C4 intermediate species had the lowest export rather than the C3 species. At ambient CO2, immediate export was strongly correlated with photosynthesis. However, at 90 Pa CO2, when photosynthesis and immediate export increased in all C3 and C3‐C4 intermediate species, proportionally less C was exported in all photosynthetic types than that at ambient CO2. All species accumulated starch and sugars at both CO2 levels. There was no correlation between immediate export and the pattern of 14C‐labelling into sugars and starch among the photosynthetic types within each genus. However, during CO2 enrichment, C4Panicum species accumulated sugars above the level of sugars and starch normally made at ambient CO2, whereas the C4Flaveria species accumulated only additional starch. 相似文献
16.
17.
Several niobium and tantalum compounds were prepared that contain either the diamidoamine ligand, [(3,4,5-F3C6H2NCH2CH2)2NMe]2− ([F3N2NMe]2−), or the triamidoamine ligand, [(3,5-Cl2C6H3NCH2CH2)3N]3− ([Cl2N2NMe]3−). The former include [F3N2NMe]TaCl3, [F3N2NMe]NbCl3, [F3N2NMe]TaMe3, [F3N2NMe]NbMe3, [(F3N2NMe)TaMe2][MeB(C6F5)3], [F3N2NMe]Ta(CHSiMe3)(CH2SiMe3), [F3N2NMe]Ta(CH2-t-Bu)Cl2, [F3N2NMe]Ta(CH-t-Bu)(CH3), and [F3N2NMe]Ta(η2-C2H4)(CH2CH3). The latter include [Cl2N2NMe]TaCl2, [Cl2N2NMe]TaMe2, [Cl2N2NMe]Ta(η2-C2H4), and [Cl2N2NMe]Ta(η2-C2H2).X-ray diffraction studies were carried out on [F3N2NMe]Ta(CHSiMe3)(CH2SiMe3), [F3N2NMe]Ta(η2-C2H4)(CH2CH3), and [Cl2N2NMe]TaMe2.. 相似文献
18.
Thomas C.W. Mak 《Inorganica chimica acta》1985,109(2):131-133
The title compound has been synthesized and subjected to crystal structure analysis. Mr = 548.50, m.p. 108.1 °C (decom.), orthorhombic, Im2m,a = 7.006(2), b = 8.938(2), c = 13.619(2) Å V = 852.8(3) Å3, Z = 2, Dx = 2.136, Dm, (flotation in CCl4/CH2I2) = 2.128 g cm?3, λ(Mo-Kα) = 0.71069 Å, μ = 90.79 cm?1, F(000) = 519.89, T = 295 K, final RF = 0.036 and RG = 0.044 for 566 observed reflections. The discrete [UO2F4(H20)]2? anion has site symmetry m2m, its virtually linear uranyl moiety being surrounded by fluoro and aquo ligands occupying the vertices of a pentagon in the equatorial plane. Watet molecules serve to link the complex anions by hydrogen bonds into layers, between which the organic cations are accommodated. 相似文献
19.
Al4(C5Me4H)4: Structure, reactivity and bonding 总被引:1,自引:0,他引:1
Michael Huber 《Inorganica chimica acta》2008,361(2):457-461
The synthesis of Al4R4 (R = C5(CH3)4H) (3) and the tetrahedral structure in the solid state are described. These results as well as the 27Al NMR spectra of 3 in solution are in line with the data obtained from DFT calculations. These calculations also support the failed observation of a monomeric AlR species in solution. Monomeric and tetrameric molecules of 3 are discussed with respect to those of (AlCp∗)4 (1) and (AlCp)4 (2). The increasing Al-Al bond strength from 1 to 3 and 2 from X-ray data is also supported by structural and energetic results from DFT calculations. 相似文献
20.
The effect of six naturally occurring prostaglandins on isolated umbilical arteries and veins has been studied. All six prostaglandins had a constricting effect on the umbilical vessels. On the umbilical artery preparations the potencies in decreasing order were A2>B2>F2α>B1>E2>A1. Prostaglandin B2 was more potent than PGA2 on the umbilical vein. Polyphloretin phosphate (PPP) antagonised the constricting effect of all six prostaglandins without altering responses to 5-hydroxytryptamine. 相似文献