Synthesis, characterization and biological activity of organotitanium substituted heteropolytungstates

Wang, Xiaohong; Liu, Jingfu; Chen, Ya-Guang; Li, Qun; Liu, Jutao; Pope, Michael T.

doi:10.1039/a907370a

Cited by 55 publications

(35 citation statements)

References 8 publications

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“…In aqueous solutions with mercury electrodes, the Ti IV center is reduced to the Ti III state and the corresponding process is usually found at a less-negative potential than the onset reduction potential of W VI centers. [5,6] The same situation seems to prevail when a glassy-carbon working electrode was used in aqueous media [7,8] even though the clear assignment of the Ti IV to Ti III wave was not always shown. In acetonitrile solution, the focus was directed on the influence of protonation on the cyclic voltammogram waves run on a glassy carbon electrode.…”

Section: Introductionmentioning

confidence: 99%

“…POMs are usually composed of early transition-metal MO 6 (M: W 6 + , Mo 6 + , V 5 + , Nb 5 + , Ta 5 + ) octahedra and main-group XO 4 (X: P, Si, and so on) tetrahedra.…”

Section: Introductionmentioning

confidence: 99%

“…Among recent achievements, experiments carried out with mercury working electrodes in acetate buffer [5,6] and on glassy-carbon working electrodes in aqueous solutions, [7,8] or in acetonitrile, [3a, 9] are illustrative of the main behavior of these complexes. In aqueous solutions with mercury electrodes, the Ti IV center is reduced to the Ti III state and the corresponding process is usually found at a less-negative potential than the onset reduction potential of W VI centers.…”

Section: Introductionmentioning

confidence: 99%

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Dititanium‐Containing 19‐Tungstodiarsenate(III) [Ti₂(OH)₂As₂W₁₉O₆₇(H₂O)]⁸⁻: Synthesis, Structure, Electrochemistry, and Oxidation Catalysis

Hussain

Bassil

Kortz

et al. 2007

Chemistry A European J

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The dititanium-containing 19-tungstodiarsenate(III) [Ti(2)(OH)(2)As(2)W(19)O(67)(H(2)O)](8-) (1) has been synthesized and characterized by IR, TGA, elemental analysis, electrochemistry, and catalytic studies. Single-crystal X-ray analysis was carried out on Cs(8)[Ti(2)(OH)(2)As(2)W(19)O(67)(H(2)O)].2CsCl.12H(2)O (Cs-1), which crystallizes in the monoclinic system, space group P2(1)/m, with a=12.7764(19), b=19.425(3), c=18.149(3) A, beta=110.234(3) degrees, and Z=2. Polyanion 1 comprises two (B-alpha-As(III)W(9)O(33)) Keggin moieties linked through an octahedral {WO(5)(H(2)O)} fragment and two unprecedented square-pyramidal {TiO(4)(OH)} groups, leading to a sandwich-type structure with nominal C(2v) symmetry. Synthesis of 1 was accomplished by reaction of TiOSO(4) and K(14)[As(2)W(19)O(67)(H(2)O)] in a 2:1 molar ratio in aqueous, acidic medium (pH 2). Polyanion 1 could also be isolated as a tetra-n-butyl ammonium (TBA) salt, {(n-C(4)H(9))(4)N}(5)H(3)[Ti(2)(OH)(2)As(2)W(19)O(67)(H(2)O)] (TBA-1). TBA-1 was studied by cyclic voltammetry in acetonitrile (MeCN) solutions containing 0.1 M LiClO(4) and compared with the results obtained with Cs-1 in aqueous media. In MeCN, the Ti(IV) and W(VI) waves could not be separated distinctly. An important adsorption phenomenon on the glassy carbon working electrode was encountered both in cyclic voltammetry and in controlled potential electrolysis and was confirmed by Electrochemical Quartz Crystal Microbalance (EQCM) studies on a carbon film. TBA-1, dissolved in MeCN, reacts with H(2)O(2) to give peroxo complexes stable enough for characterization by UV-visible spectroscopy, cyclic voltammetry, and EQCM. TBA-1 shows high catalytic activity (TOF=11.3 h(-1)) in cyclohexene oxidation with aqueous H(2)O(2) producing products typical of a heterolytic oxidation mechanism. The stability of TBA-1 under turnover conditions was confirmed by using IR, UV-visible spectroscopy as well as cyclic voltammetry.

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Section: Introductionmentioning

confidence: 99%

“…POMs are usually composed of early transition-metal MO 6 (M: W 6 + , Mo 6 + , V 5 + , Nb 5 + , Ta 5 + ) octahedra and main-group XO 4 (X: P, Si, and so on) tetrahedra.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dititanium‐Containing 19‐Tungstodiarsenate(III) [Ti₂(OH)₂As₂W₁₉O₆₇(H₂O)]⁸⁻: Synthesis, Structure, Electrochemistry, and Oxidation Catalysis

Hussain

Bassil

Kortz

et al. 2007

Chemistry A European J

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“…(Rhule, Hill, & Judd, 1998;Kortza et al, 2009). In the studies on the therapeutic effects of POMs against cancer and leukemia, it was proved that the anti-tumor activity of [Mo 7 O 24 ] 6− is even better than that of certain commercially available drugs such as cisplatin (Wang et al, 2000(Wang et al, , 2003. These properties can be attributed to their molecular and electronic structural versatility and reactivity (Casan-Pastor & Gomez-Romero, 2004).…”

Section: Introductionmentioning

confidence: 99%

A novel chitosan/polyoxometalate nano-complex for anti-cancer applications

Menon¹,

Thomas²,

Narayanan³

et al. 2011

Carbohydrate Polymers

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“…Heteropolyanions (HPA) are an important class of inorganic cage like structures which have received widespread attention over the past few decades, primarily due to their wide range of applications in fields such as medicine [1][2][3][4][5], catalysis [6][7][8][9][10][11][12] and molecular materials [13][14][15], just to name a few. One of the most studied HPA families is that of the Dawson HPA,…”

Section: Introductionmentioning

confidence: 99%

Solution and solid phase electrochemical behaviour of [Os(bpy)3]3[P2W18O62]

Fay¹,

Dempsey²,

McCormac³

2005

Electrochimica Acta

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Abstract[Os (bpy) indicating surface based processes were present. Electroactive films of the complex were formed on carbon macroelectrodes by the redox switching of the transition metal within the complex. Voltammetric investigations into the film's behaviour in a range of buffer solutions (pH 2.0, 4.5 and 7.0) were performed. The films were found to possess better stability in acidic pH and the same pH dependence for the tungsten-oxo framework of the heteropolyanions as in solution. Solid state electrochemical measurements on mechanically attached microparticles of the complex were performed, with the effect of both the nature and concentration of the aqueous electrolyte on this behaviour being investigated. Upon redox switching between the Os 2+/3+ redox states there is an associated insertion/expulsion of anions from/to the solution phase. Scanning electron micrographs of these solid state films were attained before and after redox cycling. Apparatus and ProceduresThe reference electrode that was employed in organic solvents was a silver wire in contact IR SpectroscopyThe Differential pulse anodic stripping voltammetric (DPASV) experiments were performed so as to confirm the adsorption phenomenon observed in 0.01M electrolyte concentration. Figure 3 illustrates the DPASV of a modified carbon electrode in 0.1M Et 4 NPF 6 after an accumulation step at - As discussed in the previous section the oxidative processes of the Os 2+ centre exhibits characteristics pointing to an interaction between the complex and the electrode surface. As a result a film of the complex could be deposited onto the electrode surface by continuous redox switching through the osmium metal redox couple. Films were formed by cycling the potential of the glassy carbon electrode through the Os 3+/2+ redox process for 250 cycles from 9 a 0.1M TBAPF 6 DMSO solution of the starting complex. Figure 4 [79,80]. Despite the FWHM pointing to the first redox process being monoelectronic we believe it is bielectronic for two reasons. At slower scan rates a slight shoulder has been observed on the first redox process and it is well known that the first two monoelectronic processes are very close in potential. Secondly it is well know that the parent HPA can accept 6 electrons reversibly.The P 2 W 18 O 62 6-Dawson species is stable in pH's from 2.00 to 8.00 and its electrochemical behaviour depends upon the pH of the contacting electrolyte with some of the tungsten-oxo based redox processes involving protonation [75]. As a result we were interested in investigating the effect of solution pH on the redox activity of the film. With increasing pH, the losses. The lower stability of the film towards redox cycling in pH 4.50 is linked to the pH dependent nature of the tungsten-oxo reductions, when at more alkaline pH's the availability of protons which accompany the reductions is less, relative to that in pH 2.00. Scan rate studies were also performed at both pH 2.00 and 4.50, it was found that the peak potentials were independent of scan rate and th...

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Synthesis, characterization and biological activity of organotitanium substituted heteropolytungstates

Cited by 55 publications

References 8 publications

Dititanium‐Containing 19‐Tungstodiarsenate(III) [Ti₂(OH)₂As₂W₁₉O₆₇(H₂O)]⁸⁻: Synthesis, Structure, Electrochemistry, and Oxidation Catalysis

Dititanium‐Containing 19‐Tungstodiarsenate(III) [Ti₂(OH)₂As₂W₁₉O₆₇(H₂O)]⁸⁻: Synthesis, Structure, Electrochemistry, and Oxidation Catalysis

A novel chitosan/polyoxometalate nano-complex for anti-cancer applications

Solution and solid phase electrochemical behaviour of [Os(bpy)3]3[P2W18O62]

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Synthesis, characterization and biological activity of organotitanium substituted heteropolytungstates

Cited by 55 publications

References 8 publications

Dititanium‐Containing 19‐Tungstodiarsenate(III) [Ti2(OH)2As2W19O67(H2O)]8−: Synthesis, Structure, Electrochemistry, and Oxidation Catalysis

Dititanium‐Containing 19‐Tungstodiarsenate(III) [Ti2(OH)2As2W19O67(H2O)]8−: Synthesis, Structure, Electrochemistry, and Oxidation Catalysis

A novel chitosan/polyoxometalate nano-complex for anti-cancer applications

Solution and solid phase electrochemical behaviour of [Os(bpy)3]3[P2W18O62]

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Product

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Dititanium‐Containing 19‐Tungstodiarsenate(III) [Ti₂(OH)₂As₂W₁₉O₆₇(H₂O)]⁸⁻: Synthesis, Structure, Electrochemistry, and Oxidation Catalysis

Dititanium‐Containing 19‐Tungstodiarsenate(III) [Ti₂(OH)₂As₂W₁₉O₆₇(H₂O)]⁸⁻: Synthesis, Structure, Electrochemistry, and Oxidation Catalysis