Multicomponent Polyanions. 46. Characterization of the Isomeric Keggin Decamolybdodivanadophosphate Ions In Aqueous Solution by 31P and 51V NMR

Pettersson, Lage; Andersson, Ida; Grate, John H.; Selling, Anna

doi:10.1021/ic00083a023

Cited by 140 publications

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“…was used to probe silicaNH 2 -PMo 10 V 2 and silicaNH 2 -PMo 11 V materials. Solid H 4 [PMo 11 VO 40 ] AE 10H 2 O has one 31 P resonance at ) 3.55 ppm with Dm 1/2 = 64 Hz (in water also one signal appears at similar shift, which is in agreement with literature data [29]). However, when the polyoxoanion was immobilized on the silicaNH 2 , the phosphorus resonance was shifted to ) 4.1 ppm (a difference of about 0.5 ppm) maintaining similar half width (Dm 1/2 = 72 Hz).…”

Section: Coordination Environment Of Co II and Mn Iii After Supportinsupporting

confidence: 90%

“…Deconvolution analysis of the 31 P MAS n.m.r. spectrum showed the resonances at ) 2.5 ppm (8%), and ) 3.1 to ) 3.6 ppm (92%), whereas the former is attributed to contaminant ''PMo 9 V 3 '' and the later to the different positional isomers of PMo 10 V 2 [29]. Surprisingly, only one signal has been observed in 31 P MAS n.m.r.…”

Section: Coordination Environment Of Co II and Mn Iii After Supportinmentioning

confidence: 93%

“…The rotor was spun in air at 5 kHz. 29 Si MAS n.m.r. spectra were recorded at 79.49 MHz on a 9.4T Brucker Avance-400 spectrometer, using a 45°p ulses with a spinning rate of 5 kHz and a 60 s recycle delay.…”

Section: Reagents and Methodsmentioning

confidence: 99%

“…Samples were evacuated at 120°C for 8 h before the analysis. 29 Si-1 H solid-state magic angle spinning (MAS) n.m.r. with cross-polarization (CP) spectra were recorded at 79.49 MHz on a 9.4T Brucker Avance-400 spectrometer, using a contact time of 8 ms, a recycle delay of 5 s and a 1 H 90°pulse of 4 ls.…”

Section: Reagents and Methodsmentioning

confidence: 99%

“…The drop of specific surface area determined using BET method after POM immobilization on functionalized mesoporous silica or MCM-41 was previously observed for related materials and attributed to the partial filling/blockage of pores with POM clusters [16][17][18][19][20]. 29 Si-n.m.r. of the synthesised silicaNH 2 -POM materials showed signals at ) 68 ppm (8%), ) 102 ppm (32%) and ) 111.5 ppm (60%) (Fig.…”

Section: Preparation and Characterization Of Silicanh 2 -Pom Materialsmentioning

confidence: 97%

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Transition metal substituted polyoxometalates supported on amine-functionalized silica

Gamelas

Evtuguin

Esculcas

2007

Transition Met Chem

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A series of transition metal substituted polyoxometalates (POM) have been anchored to propylamine-functionalized mesoporous silica (silicaNH 2 ). These include V, Co and Mn Keggin-type anions such as [PMo 10 V 2 O 40 ] 5) and [PMo 11 VO 40 ] 4) , or [SiW 11 Co II (H 2 O)O 39 ] 6) and [SiW 11 Mn III (H 2 O)O 39 ] 5) , and sandwich-type anions, [(PW 9 O 34 ) 2 Co 4 II (H 2 O) 2 ] 10) and [(PW 9 O 34 ) 2 Mn 4 II (H 2 O) 2 ] 10). Experiments at different initial pH i of aqueous suspension of silica were performed for the Co and Mn substituted Keggin anions. The novel silicaNH 2 -POM materials having between 12-17% (w/w) of polyoxometalate were characterized by elemental analysis, solid-state 29 Si, 13 C and 31 P 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 pH i ‡ 5.5 or the electrostatic bonding between polyoxoanion and protonated C 3 H 6 NH 3 + group at pH i = 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. 31 P MAS n.m.r. showed a shifting of phosphorus atom resonances in H 5 [PMo 10 V 2 O 40 ] and H 4 [PMo 11 VO 40 ] to a single resonance at ca. ) 4.1 ppm (Dm 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 C 3 H 6 NH 3 + groups.

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Section: Coordination Environment Of Co II and Mn Iii After Supportinsupporting

confidence: 90%

Section: Coordination Environment Of Co II and Mn Iii After Supportinmentioning

confidence: 93%

Section: Reagents and Methodsmentioning

confidence: 99%

Section: Reagents and Methodsmentioning

confidence: 99%

Section: Preparation and Characterization Of Silicanh 2 -Pom Materialsmentioning

confidence: 97%

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Transition metal substituted polyoxometalates supported on amine-functionalized silica

Gamelas

Evtuguin

Esculcas

2007

Transition Met Chem

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Thermochemical Study of Reduction and Oxidation Reactions of Molybdovanadophosphoric Heteropolyacids in Aqueous Solutions

Жижина¹,

Odyakov

Matveev

1999

Eur. J. Inorg. Chem.

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Differential enthalpies of reduction, –ΔrH4j, have been found at 343 K for 0.2 m aqueous heteropolyacids H3+xPVxMo12–xO40 (HPA‐x, where 1 ≤ x ≤ 6) and their salts by hydrazine hydrate (HH). The –ΔrH4j values depend on x and m, where m = [VIV]/[HPA‐x]. At m ≈ 0, the initial –ΔrH4j value is 436 ± 14 kJ mol−1 HH for all HPA‐x. For HPA‐x with 3 ≤ x ≤ 6, the curves –ΔrH4j = f(mj) have maxima associated with formation and reduction of the outer‐sphere cation VVVIVO33+. A similar maximum is observed on reduction of 0.1 M VO2ClO4 in 4 M HClO4. No maxima are observed for the reduction of HPA‐1, HPA‐2, and salts of HPA‐3. For HPA‐3 salts, –ΔrH4j = f(mj) depends primarily on the pH of the salt solution, rather than on the nature of the cation. Reduction and oxidation of HPA‐x and their salts are reversible reactions. In HPA‐x solutions, VO2+ in the outer sphere is reduced first, and VV in the inner coordination sphere of the heteropoly anion is reduced next. Differential enthalpies for the oxidation of the reduced HPA‐x by dioxygen (–ΔrH2j) have been calculated. The sequence of the oxidation of different VIV forms in the reduced HmHPA‐x solutions is the reverse of that for the reduction of the VV forms in the initial HPA‐x solutions.

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Polyoxometalate oxidation of chemical warfare agent simulants in fluorinated media

Johnson

Hill

1999

J of Applied Toxicology

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Multicomponent Polyanions. 46. Characterization of the Isomeric Keggin Decamolybdodivanadophosphate Ions In Aqueous Solution by 31P and 51V NMR

Cited by 140 publications

References 0 publications

Transition metal substituted polyoxometalates supported on amine-functionalized silica

Transition metal substituted polyoxometalates supported on amine-functionalized silica

Thermochemical Study of Reduction and Oxidation Reactions of Molybdovanadophosphoric Heteropolyacids in Aqueous Solutions

Polyoxometalate oxidation of chemical warfare agent simulants in fluorinated media

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