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1.
Electrospray ionization (ESI) of the Lindqvist (n-Bu4N)2[M6O19] (M = Mo, W) polyoxometalates provides a straightforward entry for the generation of an assortment of oxo- and hydroxo anions
in the gas-phase. In particular, the series of oxo dianions of general formula [(MO3)
n
O]2− (n = 2–6; M = Mo, W), monoanions, namely [(MO3)
n
O]− (n = 1, 2) and [(MO3)
n
]− (n = 1, 2), and the hydroxo [(MO3)
n
(OH)]− (n = 1–6) species can be readily generated in the gas-phase upon varying the solvent composition as well as the ionisation conditions
(typically the Uc cone voltage). Complementary tandem mass experiments (collision induced dissociation and ion–molecule reactions) are also
used aimed to investigate the consecutive dissociation of these species and their intrinsic gas-phase reactivity towards methanol.
Special emphasis is paid to some of the key factors of these group 6 anions related to the gas-phase activation of methanol,
such as molecular composition, open vs closed shell electronic nature and cluster size. 相似文献
2.
Summary. tris-(Benzimidazol-2-yl-methyl)-amine, H3
ntb, was prepared and used in the synthesis of dinuclear Ru(II) polypyridyl and polynuclear Ru(II)–Co(III) complexes of the type
[Ru2(H2
ntb) (bpy)4]3+, [Ru2(Hntb)(phen)4]2+, [(Ru2(H2
ntb)(bpy)4)2Co(en)2]9+, and [(Ru2(Hntb)(phen)4)2 Co(en)2]7+ (bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, en = 1,2-diaminoethane). The complexes were characterized by elemental analysis as well as spectroscopic and redox data. The
luminescent properties of the complexes were also studied. The complexes showed significant antitumour and anti-HIV activities.
Received May 9, 2001. Accepted (revised) June 7, 2001 相似文献
3.
L. G. Detsuheva M. A. Fedotov L. I. Kuznetsova A. A. Vlasov V. A. Likholobov 《Russian Chemical Bulletin》1997,46(5):874-880
Unsaturated heteropolyanions (HPA) [PW11O39]7− stabilize TiIV hydroxo complexes in aqueous solutions (Ti: PW11 [PW11O39]7−⪯12, pH 1–3). Spectral studies (optical,17O and31P NMR, and IR spectra) and studies by the differential dissolution method demonstrated that TiIV hydroxo complexes are stabilized through interactions of polynuclear TiIV hydroxo cations with heteropolyanions [PW11TiO40
5− formed. Depending on the reaction conditions, hydroxo cations Ti
n−1O
x
H
y
m+ either add to oxygen atoms of the W−O−Ti bridges of the heteropolyanions to form the complex [PW11TiO40·Ti
n−1O
x
H
y
]
k−
(at [HPA]=0.01 mol L−1) or interact with TiIV of the heteropolyanions through the terminal o atom to give the polynuclear complexes [PW11O39Ti−O−Ti
n−1O
x
H
y
]q− (at [HPA]=0.2 mol L−1). When the complexes of the first type were treated with H2O2, TiIV ions added peroxo groups.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 914–920, May, 1997. 相似文献
4.
Zhiming Zhang Shuang Yao Enbo Wang Quan Shi Hong Zhang 《Journal of Cluster Science》2008,19(3):521-530
Two new tungstogermanates K2Na10[Cu4(GeW9O34)2] · 15.5H2O (1) and K4Na6[Cu3.5W0.5(H2O)2(GeW9O34)2] · 17H2O (2) have been obtained by the conventional aqueous solution methods and characterized by IR, element analysis, electrochemistry
and single-crystal X-ray analysis. Compound 1 is composed of the [Cu4(GeW9O34)2]12− anions linked by two equivalent bonds of Cu–O–W, representing the first one-dimensional chain-like structure based on sandwich-type
polyoxometalates by direct condensation to form oxo-bridged arrays of clusters. Compound 2 is a sandwich structure, consisting of two trivacant [GeW9O34]10− units linked by a [Cu3.5W0.5(H2O)2] cluster, and the anions are linked by the K+ and Na+ to form a three-dimensional structure.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
5.
The two new compounds Mn(dien)2[MoS4] (1) and Mn(dien)2[Mo2O2S6] (2) (dien = diethylenetriamine) were prepared under solvothermal conditions. Both compounds were obtained as phase-pure products. The structures consist of new [Mn(dien)2]2+ cations and isolated tetrahedral [MoS4]2− (1) or [Mo2O2S6]2− (2) anions. Between the anions and the cations, hydrogen bonding is observed. Compound 1 crystallizes in the tetragonal space group I (a = 10.219(2), c = 9.259(2) ?, Z = 2), whereas 2 crystallizes in the monoclinic space group P21/c (a = 8.703(2), b = 18.390(4), c = 14.603(3) ?, β = 103.18(3)°, Z = 4). The thermal behaviour of the thiomolybdates was investigated using difference thermoanalysis (DTA) and thermogravimetry (TG). Both compounds decompose under argon with a single endothermic signal in the DTA curve (peak maximum: 252 (1) and 242°C (2)). 相似文献
6.
M. L. Wei R. P. Sun P. F. Zhuang Y. H. Yang 《Russian Journal of Coordination Chemistry》2009,35(12):885-890
An ion crystal [Ag2L2][(n-C4H9)4N][PMo12O40] · H2O · 0.5CH3OH · 0.25 DMF (I) (DMF is N,N-dimethylformamide) has been synthesized by the complexation of metal double helix and Keggin polyanions in a DMF-CH3 OH solution and structurally characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. In compound
I [PMo12O40]3− anions and [(n-C4H9)4N]+ ions alternately arrange themselves in a special order in consistence with that of [Ag2L2]2+ metal helicates based on π-π stacking interactions, yielding a packing of complex cations and Keggin anions. 相似文献
7.
Summary. The two new compounds Mn(dien)2[MoS4] (1) and Mn(dien)2[Mo2O2S6] (2) (dien = diethylenetriamine) were prepared under solvothermal conditions. Both compounds were obtained as phase-pure products. The
structures consist of new [Mn(dien)2]2+ cations and isolated tetrahedral [MoS4]2− (1) or [Mo2O2S6]2− (2) anions. Between the anions and the cations, hydrogen bonding is observed. Compound 1 crystallizes in the tetragonal space group I (a = 10.219(2), c = 9.259(2) ?, Z = 2), whereas 2 crystallizes in the monoclinic space group P21/c (a = 8.703(2), b = 18.390(4), c = 14.603(3) ?, β = 103.18(3)°, Z = 4). The thermal behaviour of the thiomolybdates was investigated using difference thermoanalysis (DTA) and thermogravimetry
(TG). Both compounds decompose under argon with a single endothermic signal in the DTA curve (peak maximum: 252 (1) and 242°C (2)).
Received November 5, 2001. Accepted December 27, 2001 相似文献
8.
A series of transition metal substituted polyoxometalates (POM) have been anchored to propylamine-functionalized mesoporous
silica (silicaNH2). These include V, Co and Mn Keggin-type anions such as [PMo10V2O40]5− and [PMo11VO40]4−, or [SiW11CoII(H2O)O39]6− and [SiW11MnIII(H2O)O39]5−, and sandwich-type anions, [(PW9O34)2 Co
4
II
(H2O)2]10− and [(PW9O34)2Mn
4
II
(H2O)2]10−. Experiments at different initial pHi of aqueous suspension of silica were performed for the Co and Mn substituted Keggin anions. The novel silicaNH2-POM materials having between 12–17% (w/w) of polyoxometalate were characterized by elemental analysis, solid-state 29Si, 13C and 31P n.m.r., diffuse reflectance spectroscopy, FTIR spectroscopy, thermal analyses, and BET surface area measurements. The elemental
analyses and spectroscopic results pointed to the integrity of POM structures after immobilization on the silica support while
the latter one showed a slight decrease of BET surface area. Results of the visible diffuse reflectance spectroscopy for the
Co-substituted Keggin anion revealed the coordination of cobalt centers in the cluster with the nitrogen atom of amine groups
in modified silica at pHi ≥ 5.5 or the electrostatic bonding between polyoxoanion and protonated C3H6NH
3
+
group at pHi = 3.5. For the Co-substituted sandwich anion, external Co centres of the polyoxoanion have coordinated with the amine groups
of modified silica under the experimental conditions used. 31P MAS n.m.r. showed a shifting of phosphorus atom resonances in H5[PMo10V2O40] and H4[PMo11VO40] to a single resonance at ca. − 4.1 ppm (Δv
1/2 ~ 70 Hz) when these POM were immobilized on the functionalized silica under weak acidic conditions (pH 3), evidencing electrostatic
interaction of POM clusters with the C3H6NH
3
+
groups. 相似文献
9.
Shangyun Ye Yongyao Xia Pingwei Zhang Zhiyu Qiao 《Journal of Solid State Electrochemistry》2007,11(6):805-810
A series of the mixed transition metal compounds, Li[(Ni1/3Co1/3Mn1/3)1–x-y
Al
x
B
y
]O2-z
F
z
(x = 0, 0.02, y = 0, 0.02, z = 0, 0.02), were synthesized via coprecipitation followed by a high-temperature heat-treatment. XRD patterns revealed that
this material has a typical α-NaFeO2 type layered structure with R3-
m space group. Rietveld refinement explained that cation mixing within the Li(Ni1/3Co1/3Mn1/3)O2 could be absolutely diminished by Al-doping. Al, B and F doped compounds showed both improved physical and electrochemical
properties, high tap-density, and delivered a reversible capacity of 190 mAh/g with excellent capacity retention even when
the electrodes were cycled between 3.0 and 4.7 V. 相似文献
10.
Yan Ding Hongli Chen Weilin Chen Enbo Wang Jingxin Meng 《Transition Metal Chemistry》2009,34(3):281-288
Four novel organic–inorganic hybrid compounds [Cu5
I(4,4′-bpy)3(2,2′-bpy)4][BW12O40] · H2O (1), [Ni0.5(2,2′-bpy)1.25][Ni(2,2′-bpy)3][Ni(2,2′-bpy)2(H2O)(SiW11VIWVO40)] · 0.5H2O (2), [H2bpy]2[Zn(2,2′-bpy)3]2[Si2W18O62] · 1.5H2O (3) and [CuII(2,2′-bpy)2]2[SiW12O40] · 2H2O (4) (2,2′-bpy = 2,2′-bipyridine, 4,4′-bpy = 4,4′-bipyridine) have been synthesized under hydrothermal conditions and characterized
by elemental analysis, IR spectroscopy, thermal gravimetric analysis, electrochemical measurements and single-crystal X-ray
diffraction. Compound (1) is a novel [BW12O40]5− polyoxoanion bisupported by copper(I) coordination cations with mixed 2,2′-bpy and 4,4′-bpy ligands. Compound (2) is constructed from the [SiW11VIWVO40]5− polyoxoanions supported by [Ni(2,2′–bpy)2]2+. Compound (3) is composed of a novel [Si2W18O62]8− cluster and [Zn(2,2′–bpy)3]2+ complexes, which held together into a three-dimensional (3D) supramolecular network through hydrogen-bonding interactions.
Compound (4) shows a 2D layer framework constructed from a bisupporting Keggin polyoxoanion cluster and [Cu(2,2′–bpy)2]2+ coordination polymer fragments, resulting in 3D networks via supramolecular interactions.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
11.
Charles W. Bock George D. Markham Amy K. Katz Jenny P. Glusker 《Theoretical chemistry accounts》2006,115(2-3):100-112
Structural features of clusters involving a metal ion (Li+, Na+, Be2+, Mg2+, Zn2+, Al3+, or Ti4+) surrounded by a total of 18 water molecules arranged in two or more shells have been studied using density functional theory.
Effects of the size and charge of each metal ion on the organization of the surrounding water molecules are compared to those
found for a Mg[H2O]62+• [H2O]12 cluster that has the lowest known energy on the Mg2+• [H2O]18 potential energy surface (Markham et al. in J Phys Chem B 106:5118–5134, 2002). The corresponding clusters with Zn2+ or Al3+ have similar structures. In contrast to this, clusters with a monovalent Li+ or Na+ ion, or with a very small Be2+ ion, differ in their hydrogen-bonding patterns and the coordination number can decrease to four. The tetravalent Ti4+ ionizes one inner-shell water molecule to a hydroxyl group leaving a Ti4+(H2O)5 (OH−) core, and an H3O+• • • H2O moiety dissociates from the second shell of water molecules. These observations highlight the influence of cation size and
charge on the local structure of hydrated ions, the high-charge cations causing chemical changes and the low-charge cations
being less efficient in maintaining the local order of water molecules.
Electronic Supplementary Material: Supplementary material is available for this article at http://dx.doi.org/10.1007/S00214-005-0056-2. 相似文献
12.
B. Das M. V. Reddy G. V. Subba Rao B. V. R. Chowdari 《Journal of Solid State Electrochemistry》2011,15(2):259-268
Nano-composites of SnO(V2O3)
x
(x = 0, 0.25, and 0.5) and SnO(VO)0.5 are prepared from SnO and V2O3/VO by high-energy ball milling (HEB) and are characterized by X-ray diffraction (XRD), scanning electron microscopy, and
high-resolution transmission electron microscopy techniques. Interestingly, SnO and SnO(VO)0.5 are unstable to HEB and disproportionate to Sn and SnO2, whereas HEB of SnO(V2O3)
x
gives rise to SnO2.VO
x
. Galvanostatic cycling of the phases is carried out at 60 mA g−1 (0.12 C) in the voltage range 0.005–0.8 V vs. Li. The nano-SnO(V2O3)0.5 showed a first-charge capacity of 435 (±5) mAh g−1 which stabilized to 380 (±5) mAh g−1 with no noticeable fading in the range of 10–60 cycles. Under similar cycling conditions, nano-SnO (x = 0), nano-SnO(V2O3)0.25, and nano-SnO(VO)0.5 showed initial reversible capacities between 630 and 390 (±5) mAh g−1. Between 10 and 50 cycles, nano-SnO showed a capacity fade as high as 59%, whereas the above two VO
x
-containing composites showed capacity fade ranging from 10% to 28%. In all the nano-composites, the average discharge potential
is 0.2–0.3 V and average charge potential is 0.5–0.6 V vs. Li, and the coulombic efficiency is 96–98% after 10 cycles. The
observed galvanostatic cycling, cyclic voltammetry, and ex situ XRD data are interpreted in terms of the alloying–de-alloying
reaction of Sn in the nano-composite “Sn-VO
x
-Li2O” with VO
x
acting as an electronically conducting matrix. 相似文献
13.
Xiao-Lan Wang Ying Lu Jing-Xin Meng En-Bo Wang Hai Fu 《Transition Metal Chemistry》2011,36(2):201-206
Three new organic–inorganic hybrid complexes based on the Wells–Dawson polyoxoanion, namely (H2bpp)[Ni2(bpp)2(H2O)4(P2W18O62)]·H2O 1, [Cu6(Hbpy)6(bpy)3(P2W18O62)2]·2H2O 2 and (Him)5[Cu(im)2(P2W18O62)]·4H2O 3 [bpp = 1,3-bis (4-pyridyl) propane, bpy = 4,4′-bipyridine, im = imidazole] have been synthesized and characterized. Complex
1 exhibits a three-dimensional (6, 3)-connected framework with anatase topology constructed from [α-P2W18O62]6− clusters and [Ni(bpp)]2+ fragments. Each [α-P2W18O62]6− anion links to six nickel atoms through six terminal oxygen atoms from four polar and two equatorial WO6 octahedra, which shows a novel coordination mode of a Wells–Dawson cluster with a transition-metal atom. Complex 2 displays an interesting one-dimensional double-chain structure built from [α-P2W18O62]6− clusters and [Cu2(bpy)(Hbpy)2]2+ fragments. To our knowledge, complex 2 represents the first double-chain organic–inorganic hybrid complex based on a Wells–Dawson-type cluster. Complex 3 possesses a one-dimensional zigzag chain structure constructed from [α-P2W18O62]6− anions and [Cu(im)2]+ units through weak Cu···O interactions. 相似文献
14.
New potassium-conducting solid electrolytes in the mixed gallate-ferrite systems (1 − x)Ga2O3 · xFe2O3 · 0.25TiO2 · K2O and 1.5[(1 − x)Ga2O3 · xFe2O3] · TiO2 · 2K2O are synthesized and studied. The electrolytes exhibit high ionic conductivity in the test temperature range of 300 to 750°C
(above 10−2 S/cm at 300°C and above 10−1 S/cm at 700°C). An increase in the conductivity with increasing concentration of iron in the specimens is a general tendency.
Possible reasons for the effect of Ga/Fe ratio in the structure of solid electrolytes on their transport properties are discussed. 相似文献
15.
Tho Thieu Duc Prasada Rao Rayavarapu Stefan Adams 《Journal of Solid State Electrochemistry》2010,14(10):1781-1786
(LiBr)
x
[(Li2O)0.6(P2O5)0.4](1 − x) glasses with 0 ≤ x ≤ 0.2 are prepared by melt quenching. Glass transition temperature (T
g), ionic conductivity (σ), and its activation energy (E
a) are determined experimentally and correlated to molecular dynamics (MD) simulations with an optimized potential, fitted
to match bond lengths, coordination numbers, and ionic conductivity. Based on equilibrated MD configurations, ion transport
pathways are modelled in detail by the bond valence approach to clarify the influence of the halide dopant concentration on
the glass structure and its consequence for Li ion mobility. Results of experimental and computational studies are compared
with our previous report on the (LiCl)
x
[(Li2O)0.6(P2O5)0.4](1 − x) system. Both T
g and σ values are higher for LiBr-doped glasses than for LiCl-doped glasses, but the effect of halide doping is unusually small. 相似文献
16.
Leavitt CM Wolk AB Kamrath MZ Garand E Van Stipdonk MJ Johnson MA 《Journal of the American Society for Mass Spectrometry》2011,22(11):1941-1952
We report vibrational predissociation spectra of the four protonated dipeptides derived from glycine and sarcosine, GlyGlyH+•(H2)1,2, GlySarH+•(D2)2, SarGlyH+•(H2)2, and SarSarH+•(D2)2, generated in a cryogenic ion trap. Sharp bands were recovered by monitoring photoevaporation of the weakly bound H2 (D2) molecules in a linear action regime throughout the 700–4200 cm–1 range using a table-top laser system. The spectral patterns were analyzed in the context of the low energy structures obtained
from electronic structure calculations. These results indicate that all four species are protonated on the N-terminus, and
feature an intramolecular H-bond involving the amino group. The large blue-shift in the H-bonded N–H fundamental upon incorporation
of a methyl group at the N-terminus indicates that this modification significantly lowers the strength of the intramolecular
H-bond. Methylation at the amide nitrogen, on the other hand, induces a significant rotation (~110o) about the peptide backbone. 相似文献
17.
A new H2O2 biosensor was fabricated on the basis of nanocomposite films of hemoglobin (Hb), silver nanoparticles (AgNPs), and multiwalled
carbon nanotubes (MWNTs)–chitosan (Chit) dispersed solution immobilized on glassy carbon electrode (GCE). The immobilized
Hb displayed a pair of well-defined and reversible redox peaks with a formal potential (E
θ′) of −22.5 mV in 0.1 M pH 7.0 phosphate buffer solution. The apparent heterogeneous electron transfer rate constants (k
s) in the Chit–MWNTs film was evaluated as 2.58 s−1 according to Laviron’s equation. The surface concentration (Γ*) of the electroactive Hb in the Chit–MWNTs film was estimated to be (2.48 ± 0.25) × 10−9 mol cm−2. Meanwhile, the Chit–MWNTs/Hb/AgNPs/GCE demonstrated excellently electrocatalytical ability to H2O2. Its apparent Michaelis–Menten constant (K
Mapp) for H2O2 was 0.0032 mM, showing a good affinity. Under optimal conditions, the biosensors could be used for the determination of H2O2 ranging from 6.25 × 10−6 to 9.30 × 10−5 mol L−1 with a detection limit of 3.47 × 10−7 mol L−1 (S/N = 3). Furthermore, the biosensor possessed rapid response to H2O2 and good stability, selectivity, and reproducibility. 相似文献
18.
G. M. Maksimov R. I. Maksimovskaya O. A. Kholdeeva M. A. Fedotov V. I. Zaikovskii V. G. Vasil’ev S. S. Arzumanov 《Journal of Structural Chemistry》2009,50(4):618-627
Heteropoly acid (HPA) H8(PW11TiO39)2O·xH2O (I) is synthesized by three different ways and studied by chemical analysis, potentiometric titration, mass-spectrometry, IR,
31P, 183W, and 17O NMR spectroscopy, thermogravimetry, and transmission electron microscopy. Anion I consists of two subparticles of the Keggin structure bridged by Ti-O-Ti. The dimeric anion exists in HPA aqueous solutions
at [I] > 0.02 M. At pH > 0.6 it splits to a [PW11TiO40]5− monomer stable up to pH ∼ 6. When heated (150–400)°C, I splits into H3PW12O40 and, apparently, H3PW10Ti2O38 without phase separation. Thermolysis products are soluble and when dissolved in water turn again into I. Complete decomposition of I to oxides occurs at ∼450°C. 相似文献
19.
Günter Grampp Stephan Landgraf Tomasz Wesierski Beata Jankowska Ewa Kalisz Dana-Maria Sabou Boryana Mladenova 《Monatshefte für Chemie / Chemical Monthly》2002,212(4):1363-1372
The kinetics of the CrO(O2)2 formation by H2O2 and Cr2O7
2− in aqueous acidic media was measured at 293 ± 2 K in a pH range between 2.5 and 3.3. Using the stopped-flow method with rapid scan UV-VIS detection, the rate law of the formation
of CrO(O2)2 was determined. For the media HClO4, HNO3 and CH3COOH, the reaction order in the Cr2O7
2− concentration was found to be 0.5. For [H2O2] as well as for [H+], the reaction was first order in all acids used. In HCl and H2SO4 media the reaction was first order in Cr2O7
2−. At T = 293 ± 2 K the rate constant for the formation of Cr(O)(O2)2 was found to be (7.3 ± 1.9) · 102 M−3/2 s−1 in HClO4. 相似文献
20.
Günter Grampp Stephan Landgraf Tomasz Wesierski Beata Jankowska Ewa Kalisz Dana-Maria Sabou Boryana Mladenova 《Monatshefte für Chemie / Chemical Monthly》2002,133(10):1363-1372
Summary. The kinetics of the CrO(O2)2 formation by H2O2 and Cr2O7
2− in aqueous acidic media was measured at 293 ± 2 K in a pH range between 2.5 and 3.3. Using the stopped-flow method with rapid scan UV-VIS detection, the rate law of the formation
of CrO(O2)2 was determined. For the media HClO4, HNO3 and CH3COOH, the reaction order in the Cr2O7
2− concentration was found to be 0.5. For [H2O2] as well as for [H+], the reaction was first order in all acids used. In HCl and H2SO4 media the reaction was first order in Cr2O7
2−. At T = 293 ± 2 K the rate constant for the formation of Cr(O)(O2)2 was found to be (7.3 ± 1.9) · 102 M−3/2 s−1 in HClO4.
Corresponding author. E-mail: grampp@ptc.tu-graz.ac.at
Received January 30, 2002; accepted (revised) June 5, 2002 相似文献