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1.
A Mg,Al layered double hydroxide (LDH) with [Cr(C(2)O(4))(3)](3)(-) anions in the interlayer has been synthesized following two different routes: reconstruction from a mildly calcined Mg,Al-carbonate LDH, and anion exchange from a Mg,Al-nitrate LDH. The solids prepared have been characterized by elemental chemical analysis, powder X-ray diffraction, FT-IR and UV-vis/DR (diffuse reflectance) spectroscopies, thermal methods, nitrogen adsorption at -196 degrees C, and FT-IR monitoring of pyridine adsorption. The results obtained indicate that the most appropriate method is anion exchange, leading to a well crystallized LDH with an interlayer spacing of 10 A. Due to the high pH value (>8) of the solution in the reconstruction method, however, a polyphasic system is obtained, where, in addition to a phase with the LDH structure, amorphous magnesium oxalate and chromium oxohydroxides are also formed due to hydrolysis of the complex. The interlayer complex is stable up to 200 degrees C, but the layered structure is stable up to 330 degrees C, probably because of the presence of interlayer oxalate anions formed during decomposition of the complex. Calcination leads to oxidation of Cr(3+) ions to the six-valent state, which reverts to Cr(3+) when the calcination temperature is further increased.  相似文献   

2.
Ligand LH(2), composed of two bipyridylcarboxylate fragments linked to an amino butyl chain, reacts with europium and terbium to form luminescent complexes in water at neutral pH. When testing these unsaturated complexes as anion sensors with NO(3)(-), HPO(4)(2)(-), AMP, ADP, and ATP, a marked selectivity is observed for HPO(4)(2)(-) and ATP(4)(-) at pH = 7.0. The interaction of these anions with the complex was investigated by means of absorption and emission spectroscopies. With ATP(4)(-), ES-MS and (31)P NMR experiments revealed the formation of a [Ln.L.(ATP)](3)(-) ternary species.  相似文献   

3.
研究了利用铝酸钠溶液碳酸化产生的沉淀, 经胶溶作用制备出纳米氢氧化铝溶胶的过程. 分析了铝酸钠溶液滴加到大量碳酸氢钠溶液中时发生的反应. X射线衍射研究结果表明, 在纳米氢氧化铝溶胶制备过程中, 从无定形氢氧化铝沉淀到拟薄水铝石的晶型转变过程是氢氧化铝沉淀胶溶时溶解再析出的过程. 将碳酸氢钠加入到苛性比为1.7的铝酸钠溶液中, 中和至苛性比为1.3后, 溶液诱导期中的紫外光谱显示270 nm处的Al(OH)3-6吸收增强. 经与含铝原子六配位的晶体紫外光谱对比后表明, 在铝酸钠分解生成氢氧化铝的过程中, 其铝的配位结构从四配位转化为六配位. 拟薄水铝石溶胶粒子的形貌与胶溶所用的酸和分散剂有关.  相似文献   

4.
Raman spectroscopy has been used to characterise nine hydrotalcites prepared from aluminate and magnesium solutions (magnesium chloride and seawater). The aluminate hydrotalcites are proposed to have the following formula Mg(6)Al(2)(OH)(16)(CO(3)(2-))·xH(2)O, Mg(6)Al(2)(OH)(16)(CO(3)(2-),SO(4)(2-))·xH(2)O, and Mg(6)Al(2)(OH)(16)(SO(4)(2-))·xH(2)O. The synthesis of these hydrotalcites using seawater results in the intercalation of sulfate anions into the hydrotalcite interlayer. The spectra have been used to assess the molecular assembly of the cations and anions in the hydrotalcite structures. The spectra have been conveniently subdivided into spectral features based upon the carbonate anion, the hydroxyl units and water units. This investigation has shown the ideal conditions to form hydrotalcite from aluminate solutions is at pH 14 using a magnesium chloride solution at a volumetric ratio of 1:1. Changes in synthesis conditions resulted in the formation of impurity products aragonite, thenardite, and gypsum.  相似文献   

5.
Ag(+) ion-exchanged layered aluminum dihydrogen triphosphate (AlP) with the interlayer distance of 0.85 nm was synthesized by the ion-exchange of proton in triphosphate with Ag(+) ion. The amount of exchanged Ag(+) ion depended on the concentration of AgNO(3) aqueous solution. Ag(+) ion-exchanged AlP adsorbed gaseous thiols and sulfides into the interlayer region. The adsorption amounts of thiols were more than those of sulfides, thiols with one mercapto group > thiol with two mercapto groups > sulfides, and depended on the amount of exchanged Ag(+) ion in the interlayer region. The thiols with one mercapto group were intercalated to expand the interlayer distance of Ag(+) ion-exchanged AlP, whereas there was no expansion in the adsorption of sulfide. In the case of thiol with two mercapto groups, there was observed contraction of the interlayer distance through the bridging with Ag(+) ions of the upper and lower sides of the interlayer region.  相似文献   

6.
Molecular dynamics (MD) simulations are used to study the interlayer structure, hydrogen bonding, and energetics of hydration of Mg/Al (2:1 and 4:1) layered double hydroxide (LDH) or hydrotalcite (HT) intercalated with oxymetal anions, CrO(4)(2-), and VO(4)(3-). The ab initio forcefield COMPASS is employed for the simulations. The charge on the oxymetal anions is determined by quantum mechanical density functional theory. The structural behavior of the oxymetal anions in LDH directly relates to the energetic relationships, with electrostatic and H-bonding interactions between the anions, hydroxide sites of the metal hydroxide layers, and the interlayer water molecules. Distinct minima in the hydration energy indicate the presence of energetically well-defined structural states with specific water content. The experimentally identified variability in the retention of the CrO(4)(2-) and VO(4)(3-) is well reflected in the calculations and self-diffusion coefficients obtained from the simulations give insight into the mobility of the intercalated species.  相似文献   

7.
The solid-state chelation of transition metal ions (Co(2+), Ni(2+), and Cu(2+)) from aqueous solutions into the lithium aluminum layered double hydroxide ([LiAl(2)(OH)(6)]Cl x 0.5H(2)O or LDH) which has been pre-intercalated with EDTA (ethylenediaminetetraacetate) ligand has been investigated. The intercalated metal cations form [M(edta)](2)(-) complexes between the LDH layers as indicated by elemental analysis, powder X-ray diffraction, and IR and UV-vis spectroscopies. If metal chloride or nitrate salts are used in the reaction with the LDH then co-intercalation of either the Cl(-) or NO(3)(-) anions is observed. In the case of metal acetate salts the cations intercalate without the accompanying anion. This can be explained by the different intercalation selectivity of the anions in relation to the LDH. In the latter case the introduction of the positive charge into LDH structure was compensated for by the release from the solid of the equivalent quantity of lithium and hydrogen cations. Time-resolved in-situ X-ray diffraction measurements have revealed that the chelation/intercalation reactions proceed very quickly. The rate of the reaction found for nickel acetate depends on concentration as approximately k[Ni(Ac)(2)](3).  相似文献   

8.
The adsorption isotherm of and the pH effect on the adsorption of myo-inositol hexaphosphate (myo-IP6) on amorphous aluminum hydroxide was investigated. It was found that the adsorption isotherm of myo-IP6 on aluminum hydroxide could be well fitted with the Freundlich isotherm. The amount of myo-IP6 adsorbed remained almost constant in the range of pH 4.0 to 7.0, but it decreased considerably as the initial pH was over 7. The adsorption of myo-IP6 resulted in an increase in the pH level due to the release of OH(-) ions, which suggested that the adsorption of myo-IP6 on aluminum hydroxide was caused by a ligand exchange reaction. ATR-FTIR analysis of myo-IP6 in solution and adsorbed on aluminum hydroxide at different pH were performed. The ATR-FTIR investigation indicated that myo-IP6 was adsorbed onto aluminum hydroxide by forming inner-sphere complexes and adsorption facilitated the deprotonation of phosphate groups. The asymmetric vibration of the PO bond in AlPO(-)(3) appearing at a lower frequency than that in the terminal HPO(-)(3) indicated that Al bound to the O atom not as strongly as the H atom did. The ATR-FTIR investigation and theoretical calculation (with the Gaussian 03 program) revealed that three of the six phosphate groups in myo-IP6 molecules were bound to aluminum hydroxide while the other three remained free when myo-IP6 was adsorbed on aluminum hydroxide.  相似文献   

9.
蜂王浆中磷酸腺苷的提取及超高效液相色谱分析   总被引:2,自引:0,他引:2  
比较了高氯酸提取、热水提取和热硫酸镁溶液提取3种提取方式对蜂王浆中磷酸腺苷三磷酸腺苷(ATP)、二磷酸腺苷(ADP)和单磷酸腺苷(AMP)的提取效果,发现在低温(低于4 ℃)下以5%高氯酸的提取效果最佳。采用超高效液相色谱-紫外检测法分析蜂王浆中的ATP, ADP和AMP的含量。以BEH Shield RP18柱(100 mm×2.1 mm,1.7 μm)为分析柱,以50 mmol/L的磷酸二氢铵(pH 6.5)和乙腈为流动相进行梯度洗脱,3种磷酸腺苷在4 min内实现了较好的分离。以加标王浆样品作添加回收率测定,ATP, ADP和AMP的回收率分别为84.1%~94.3%,86.2%~93.7%和91.0%~104.3%,相对标准偏差均小于10%。方法已被用于一些实际样品的分析,以了解ATP, ADP和AMP在蜂王浆样品中的分布情况。  相似文献   

10.
The removal of orthophosphates (10(-2) kg P m(-3)), condensed phosphates (10(-2) kg P m(-3)), and mixtures of both (5 x 10(-3) kg P m(-3) as orthophosphate and 5 x 10(-3) kg P m(-3) as metaphosphate) in aqueous solution is studied using alum and aluminum hydroxide. The effects of coagulant dose, pH, temperature, aging of aluminum hydroxide, and presence of different ions are investigated. On the basis of the experimental results, alum is much more efficient in phosphorus removal than aluminum hydroxide even if, in both cases, at the conditions studied, the active coagulant form is Al(OH)(3). The differences then could be due to the higher activity of the in situ formed hydroxide. Orthophosphates and metaphosphates seem to have similar behavior vs pH variation: maximum removal is achieved at pH values 5-6 in all cases. On the other hand, in the simultaneous presence of both P forms, orthophosphate and metaphosphate ions have different affinities for the surface sites of aluminum hydroxide, since for both alum and aluminum hydroxide, orthophosphates are preferentially removed compared to metaphosphates, due probably to orientation effects and the charge per P atom. The presence of sodium, potassium, magnesium, sulfate, chloride, and magnesium, at the concentrations studied and for a pH value of 6, does not influence P removal. Temperature variation, between 25 and 60 degrees C, does not affect alum efficiency but both P forms are increasingly removed with increasing temperature, probably due to polymer Al(OH)(3) breaking, producing new surfaces for adsorption. Aging decreases sorption capacity of Al(OH)(3), while crystallites of increasing size are formed. Finally adsorption of both P forms is best described by the Freundlich isotherm [[K(F)=(49.1-69.1) x 10(-3) (m(3)kg(-1))(1/N), 1/N: 0.14-0.19 for T=25-60 degrees C] and [ K(F)=(1.58-2.79) x 10(-3) (m(3)kg(-1))(1/N), 1/N: 2.17-2.47 for T=25-60 degrees C] for orthophosphate and metaphosphate, respectively.  相似文献   

11.
A new anionic clay, α-magnesium hydroxide, was synthesized by hydrolysis of magnesium acetate in propylene glycol. The structure of this α-hydroxide is similar to that of hydrotalcites. It consists of positively charged magnesium hydroxide layers arising out of partial protonation of the hydroxyl groups of the [Mg(OH)(2)] layers and loosely held anions in the interlayer region. As expected it ages readily in water to give β-magnesium hydroxide, brucite. While anion-exchange reactions of α-magnesium hydroxide could not be carried out in aqueous medium a number of anion-exchange reactions could be carried out successfully in ethanol medium.  相似文献   

12.
The novel tetranuclear copper(II) complexes with alpha-d-glucose-1-phosphates, [Cu(4)(mu-OH)(alpha-d-Glc-1P)(2)(L)(4)(H(2)O)(2)](NO(3))(3) (L = bpy (1), phen (2)), were prepared and characterized by X-ray crystallography. Complex 1 was further transformed into the ATP stabilized tetracopper(II) complex of [Cu(4)(ATP)(2)(bpy)(4)] (4), where ATP is adenosine 5'-triphosphate.  相似文献   

13.
The direct intercalation reaction of [Co(tpy)(2)](2+) with the highly hydrated θ phase of layered zirconium phosphate (θ-ZrP) resulted in the formation of the oxidized [Co(tpy)(2)](3+) ion within the ZrP material. The X-ray powder diffraction patterns showed that the interlayer distance increases from 10.3 ? in θ-ZrP to 14.9 ? in the dry [Co(tpy)(2)](3+)-intercalated ZrP {[Co(tpy)(2)](3+):ZrP} phase. The complex remains electroactive within the layers of ZrP. The formal potential of a carbon paste electrode (CPE) modified with [Co(tpy)(2)](3+):ZrP (E°' = 40.8 mV versus Ag/AgCl, 3.5 M NaCl) is non-pH-dependent. However, the sensitivity of the [Co(tpy)(2)](3+):ZrP-modified CPE for the detection of reduced nicotinamide adenine dinucleotide (NADH) electrooxidation was lower than that of a previously reported CPE modified with [Ru(phend)(2)bpy](2+)-intercalated ZrP. (1) To improve the characteristics of NADH electrooxidation of the [Co(tpy)(2)](3+):ZrP-modified CPE, we included the enzyme diaphorase in solution, which increased the electrocatalytic current for NADH oxidation. A bienzymatic lactate biosensor was constructed and used for lactate sensing.  相似文献   

14.
The synthesis and characterization of a new bis([9]aneN3) ligand (H2L) containing two [9]aneN3 macrocyclic moieties separated by a 2,2'-methylene-bis-cresol (cresol = 4-methyl-phenol) unit is reported. A potentiometric and (1)H NMR study in aqueous solution reveals that H2L is in a zwitterionic form, and protonation of the cresolate oxygens occurs only with the formation of the highly charged (H5L)(3+) and (H6L)(4+) species at acidic pH values. The coordination properties of H2L toward Cu(II), Zn(II), Cd(II), and Pb(II) were studied by means of potentiometric and UV spectrophotometric measurements. The ligand gives both mono- and binuclear complexes in aqueous solution. At acidic pH values the ligand forms stable binuclear [M2H2L](4+) complexes, where each metal is coordinated by two amine groups of [9]aneN3 and the deprotonated oxygen of the adjacent cresol unit; the remaining amine group is protonated. Deprotonation of the [M2H2L](4+) species at alkaline pH values affords [M2L](2+) complexes, where all amine groups of the [9]aneN3 moieties are involved in metal coordination. Binding of mono-, di- and triphosphate, and adenosine triphosphate (ATP) was studied by means of potentiometric, (1)H and (31)P NMR measurements and by molecular dynamics simulations. The receptor forms stable 1:1 adducts with di-, triphosphate, and ATP, while the interaction with monophosphate is too low to be detected. In the complexes both the [9]aneN3 moieties act cooperatively in the substrate binding process. The stability of the adducts increases in the order diphosphate < triphosphate < ATP. This trend is explained in terms of increasing number of charge-charge interactions between the phosphate chains and the protonated [9]aneN3 subunits and, in the case of ATP, of stacking interactions between the adenine and cresol units.  相似文献   

15.
The pharmacologically active [Ru(CO)(3)Cl(glycinate)] is shown to be in equilibrium with [Ru(CO)(2)(CO(2)H)Cl(glycinate)](-) (isomers) at around pH 3.1 which then at physiological pH reacts with more base to give [Ru(CO)(2)(CO(2))Cl(glycinate)](2-) (isomers) or [Ru(CO)(2)(CO(2)H)(OH)(glycinate)](-) (isomers). The ease with which [Ru(CO)(3)Cl(glycinate)] reacts with hydroxide results in it producing a solution in water with a pH of around 2 to 2.5 depending on concentration and making its solutions more acidic than those of acetic acid at comparable concentrations. Acidification of [Ru(CO)(3)Cl(glycinate)] with HCl gives [Ru(CO)(3)Cl(2)(NH(2)CH(2)CO(2)H)]. The crystal structures of [Ru(CO)(3)Cl(glycinate)] and [Ru(CO)(3)Cl(2)(NH(2)CH(2)CO(2)Me)] are reported.  相似文献   

16.
Son JH  Kwon YU  Han OH 《Inorganic chemistry》2003,42(13):4153-4159
By reacting Keggin-type polyoxometalate cluster anions H(2)W(12)O(40)(6)(-) (metatungstate) or Co(II)W(12)O(40)(6)(-) (tungstocobaltate) with the large aluminum cluster polycation [Al(30)O(8)(OH)(56)(H(2)O)(26)](18+), Keggin ion based molecular ionic compounds [delta-Al(13)O(4)(OH)(24)(H(2)O)(12)][XW(12)O(40)](OH).nH(2)O (X = H(2) (1) and Co (2); n congruent with 20) and [W(2)Al(28)O(18)(OH)(48)(H(2)O)(24)][H(2)W(12)O(40)](2).55H(2)O (3) were obtained. The polygon-shaped cluster ions are packed alternately through intercluster hydrogen bonds as well as electrostatic interactions, leaving large pores, which result from the packing of large clusters. The clusters are arranged in square pyramidal geometries, showing face-to-face interactions between them. The isolation of metastable [delta-Al(13)O(4)(OH)(24)(H(2)O)(12)](7+) and the formation of a new transition metal substituted aluminum heteropolycation [W(2)Al(28)O(18)(OH)(48)(H(2)O)(24)](12+) in 1-3 result from the slow fragmentation and recombination of Al(30) in the presence of suitable counter cluster anions with similar shape and charge.  相似文献   

17.
Crystalline aluminum trihydroxides Al(OH)3 (gibbsite, baverite, and nordstrandite) can serve as layered intercalation matrices in which metal salts are arranged in a specific way. Small cations (lithium, magnesium, and transition metals) lie in the octahedral voids of aluminum hydroxide layers, and water molecules are located between the layers. This localization of small cations gives rise to the molecular sieve effect, where alkaline and alkaline earth cations (Na+, K+, Ca2+, etc.), which are large relative to the octahedral voids, are not intercalated into aluminum trihydroxides. In the first step of lithium salt intercalation, the cations, the anions, and the water molecules are incorporated into the interlayer space of aluminum hydroxide with subsequent transition of lithium into the voids of the layer. Translated fromZhurnal Strukturnoi Khimii, Vol. 40, No. 5, pp. 832–848, September-October, 1999.  相似文献   

18.
The title cluster, [Pd(3)(mu(3)-CO)(dppm)(3)](2+) (dppm=bis(diphenylphosphino)methane), reacts with one equivalent of hydroxide anions (OH(-)), from tetrabutylammonium hydroxide (Bu(4)NOH), to give the paramagnetic [Pd(3)(mu(3)-CO)(dppm)(3)](+) species. Reaction with another equivalent of OH(-) leads to the zero-valent compound [Pd(3)(mu(3)-CO)(dppm)(3)](0). From electron paramagnetic resonance analysis of the reaction medium using the spin-trap agent 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), the 2-tetrahydrofuryl or methyl radicals, deriving from the tetrahydrofuran (THF) or dimethyl sulfoxide (DMSO) solvent, respectively, were detected. For both [Pd(3)(mu(3)-CO)(dppm)(3)](2+) and [Pd(3)(mu(3)-CO)(dppm)(3)](+), the mechanism involves, in a first equilibrated step, the formation of a hydroxide adduct, [Pd(3)(mu(3)-CO)(dppm)(3)(OH)]((n-1)+) (n=1, 2), which reacts irreversibly with the solvent. The kinetics were resolved by means of stopped-flow experiments and are consistent with the proposed mechanism. In the presence of an excess of Bu(4)NOH, an electrocatalytic process was observed with modest turnover numbers (7-8). The hydroxide adducts [Pd(3)(mu(3)-CO)(dppm)(3)(OH)]((n-1)+) (n=1, 2), which bear important similarities to the well-known corresponding halide adducts [Pd(3)(mu(3)-CO)(dppm)(3)(mu(3)-X)](n) (X=Cl, Br, I), have been studied by using density functional theory (DFT). Although the optimised geometry for the cluster in its +2 and 0 oxidation states (i.e., cation and anion clusters, respectively) is the anticipated mu(3)-OH form, the paramagnetic species, [Pd(3)(mu(3)-CO)(dppm)(3)(OH)](0), shows a mu(2)-OH form; this suggests an important difference in electronic structure between these three species.  相似文献   

19.
We report the interaction between B-type tri-lacunary heteropolyoxotungstate anions and actinyl(V) cations in aqueous solution, yielding a greater understanding of the stability of the O≡An≡O(1+) linear dioxo actinide moiety. Previously we reported that B-α-[BiW(9)O(33)](9-) and B-α-[SbW(9)O(33)](9-) will react with NpO(2)(1+) to yield [(Np(3)W(4)O(15))(H(2)O)(3)(MW(9)O(33))(3)](18-) (M = Bi, or Sb). Single crystal structural characterisation of salts of these complexes revealed a core in which three Np(V) atoms interact with a central W(VI) atom through bridging oxo groups. These bridging oxygen atoms come from one of the two axial oxygens in O≡Np≡O(1+) and represent a highly unusual interaction for a discrete molecular species. In this study visible/near infra-red spectroscopy indicates that [(Np(3)W(4)O(15))(H(2)O)(3)(BiW(9)O(33))(3)](18-) could be readily stabilized in solution at near neutral pH for several months, with (NH(4))(14)Na(4)[(Np(3)W(4)O(15))(H(2)O)(39)BiW(9)O(33))(3)]·62H(2)O crystallising from solution in high yield. At lower pH and [BiW(9)O(33)](9-) : NpO(2)(1+) ratios additional Np(V) species could be observed in solution. Stabilization of [(Np(3)W(4)O(15))(H(2)O)(3)(SbW(9)O(33))(3)](18-) in solution proved more challenging, with several distinctive Np(V) near infra-red transitions observed in solution. Slow complexation kinetics and reduction to Np(IV) was also observed. High [SbW(9)O(33)](9-) : NpO(2)(1+) molar ratios and careful control of solution pH was required to prepare solutions in which [(Np(3)W(4)O(15))(H(2)O)(3)(SbW(9)O(33))(3)](18-) was the only neptunium containing species. In stark contrast to the NpO(2)(1+) chemistry, [BiW(9)O(33)](9-) readily oxidizes PuO(2)(1+) to PuO(2)(2+) yielding further evidence of the decreased stability of Pu(V)vs. Np(V). Np L(II)-edge XAFS measurement revealed very good agreement with single crystal diffraction data for the Np structural environment for [(Np(3)W(4)O(15))(H(2)O)(3)(MW(9)O(33))(3)](18-) (M = Bi, or Sb) in the solid state. There was also good agreement between coordination shells for [(Np(3)W(4)O(15))(H(2)O)(3)(BiW(9)O(33))(3)](18-) in the solid state and in solution, yielding further confirmation of the high stability of this particular cluster.  相似文献   

20.
Polystyrene (PS)/aluminum hydroxide (Al(OH)(3)) composite particles were successfully prepared by the sol-gel process of aluminum isopropoxide (Al(OPr(i))(3)) in a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF(4)]) using ammonium hydroxide (NH(4)OH) as a catalyst in the presence of PS seed. Transmission electron microscopy observation of ultrathin cross-sections of the composite particles revealed that the composite particles had a core-shell morphology consisting of a PS core and a Al(OH)(3) shell having high crystallinity. The amount of secondary nucleated Al(OH)(3) could be reduced by dropwise addition of NH(4)OH. Moreover, PS/η-Al(2)O(3) composite particles were successfully prepared by heat treatment of PS/Al(OH)(3) at 300 °C in N(2) atmosphere, which is below the decomposition temperature of PS.  相似文献   

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