The solution chemistry and reactivity of lacunary Keggin silicotungstates monitored in real-time by a combination of mass spectrometry and electrochemistry

Jia, Qiaodi; Cao, Jie; Duan, Yunpeng; Hu, Changwen

doi:10.1039/c4dt02723j

Cited by 16 publications

(14 citation statements)

References 31 publications

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“…The synthesis of new POMs often occurs by template‐induced post‐functionalization or rearrangement processes of a substrate cluster into another one. To rationalize and explore these processes, ESI‐MS is commonly applied …”

Section: High‐nuclearity Pom Structures In Solutionmentioning

confidence: 99%

“…The obtained fragmentation patterns can be related to the relative energy demand of competing reactions which in turn elucidates structural details of the investigated complexes because their reactivity is commonly closely related to their structural and energetic features. CID tandem MS can also be used for the analysis of POMs, often in combination with isotopic labeling of the analyte prior to the experiment . The fragmentation of the parent cluster may lead to product ions with the same or similar stoichiometries, as observed for solution‐phase species, and can thereby give information about formation mechanisms in solution .…”

Section: High‐nuclearity Pom Structures In Solutionmentioning

confidence: 99%

“…[63] The obtained fragmentation patterns can be related to the relative energy demando fc ompeting reactions which in turn elucidates structural details of the investigated complexes because their reactivity is commonly closelyr elated to their structural and ener-getic features.C ID tandemM Sc an also be used fort he analysis of POMs, often in combination with isotopic labeling of the analyte prior to the experiment. [45,50,60] The fragmentation of the parent clusterm ay lead to product ions with the same or similars toichiometries, as observed for solution-phase species, and can thereby give information about formation mechanisms in solution. [64] However, this approach cannot be applied to all systems as the sequence of bond cleavages, starting typically with the weakest bonds, does not necessarilyr esemble the order of assembly.R ather,r eactions in the gas phase can providev aluable information on the intrinsic properties of the analyte if reactions are observed that do not occuri ns olution.…”

Section: Gas-phase Reactivity and Ion Mobilitymentioning

confidence: 99%

“…To rationalize and explore these processes, ESI-MS is commonly applied. [45,46,48,50,54,57,60,61] Cronin and co-workers presented the oscillatory guest-exchange process driven by competing redox processes in a POM capsules ystem (Figure 9a). [62] Using ESI-MS, EPR und UV/ Vis spectroscopy,t hey could demonstrate that the addition of ammonium vanadatea nd triethanolamine to their system resulted in six complete oscillations (Figure 9b).…”

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confidence: 99%

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Soluble Hetero‐Polyoxovanadates and Their Solution Chemistry Analyzed by Electrospray Ionization Mass Spectrometry

Warzok

Mahnke

Bensch

2018

Chemistry A European J

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Polyoxometalates (POMs) are an intriguing class of compounds due to their tremendous structural variety and the wide spectrum of resulting properties, which make them interesting for applications in fields such as catalysis, material science or nanotechnology. Their ability to form large supramolecular architectures by self-assembly offers an entry to complex, functional systems. After an introduction into the structure and synthesis of POMs of the early transition metals, recently discovered water-soluble antimonato polyoxovanadates (Sb-POVs) and the investigation of their chemical reactivity are discussed. Electrospray ionization mass spectrometry (ESI-MS) is presented as an analytical technique suitable to investigate the structure of complex POM assemblies in solution and to probe the underlying reactivity and formation mechanisms. This Minireview highlights the first studies on the soluble Sb-POVs and how the knowledge of their reactivity obtained by ESI-MS has fostered the syntheses of numerous novel Sb-POV compounds.

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Section: High‐nuclearity Pom Structures In Solutionmentioning

confidence: 99%

Section: High‐nuclearity Pom Structures In Solutionmentioning

confidence: 99%

Section: Gas-phase Reactivity and Ion Mobilitymentioning

confidence: 99%

mentioning

confidence: 99%

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Soluble Hetero‐Polyoxovanadates and Their Solution Chemistry Analyzed by Electrospray Ionization Mass Spectrometry

Warzok

Mahnke

Bensch

2018

Chemistry A European J

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“…6 In contrast to synthetic methods with low atom efficiencies that use stoichiometric reagents, catalytic epoxidation of alkenes with hydrogen peroxide (H 2 O 2 ) has attracted much attention, because H 2 O 2 has a high content of active oxygen species and only water is formed as a byproduct. 14 [22][23] has been applied on the study of catalytic mechanism. 12 In the catalytic process, polyoxotungstates act as catalyst precursors, which decomposed into the monomeric, dimeric and tetrameric peroxo species by the reaction with hydrogen peroxide.…”

Section: Introductionmentioning

confidence: 99%

Investigation into the mechanism of polyoxotungstates-catalyzed cyclooctene epoxidation by ESI-MS

et al. 2016

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Electronic supplementary information (ESI) available: Additional Raman spectra of different compounds and Na2WO4 solution at pH 6.8 at different concentration; ESI-MS spectra of Na2WO4 solution at pH 6.8 upon different equilibrating times. SeeThe reaction process of cyclooctene epoxidation was real-time monitored by ESI-MS using H3PW12O40 and H2WO4 as catalysts. By observing the species changes of catalysts in reaction solutions and the combination of catalysts with substrate, the mechanism of catalytic reaction of polyoxometalate clusters were proposed from the aspect of aggregation and dissociation. As H3PW12O40 was used as catalyst, it was degraded into minor peroxo-species [PW4O16-x(O2)x] 3-(x = 0, 2, 4, 6, 8) which performed as the active center of the epoxidation of cyclooctene. When H2WO4 as catalyst, it reacted with H2O2 and generated mononuclear tungsten peroxo-species [HWO2(O2)2]and [HWO2(O2)3] -. After the addition of cyclooctene, the peroxo-species catalyzed the epoxidation of cyclooctene generating 1,2-epoxycyclooctane and combined 1,2-epoxycyclooctane to form the intermediate [HW2(O2)2O5(C8H14O)2] -.

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Complex solution chemistry behind the simple “one‐pot” synthesis of vanadium‐substituted polyoxometalates unraveled by electrospray ionization mass spectrometry

Cao

Liu

Jia

2016

Rapid Comm Mass Spectrometry

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RATIONALE:The "one-pot" method is a deceptively simple and straightforward method for synthesis of polyoxometalates (POMs). However, the complex solution chemistry behind the simple method is neither clear nor elucidated thoroughly by a suitable method. In general, POM chemists are more focused on what final products are obtained by deliberately choosing the ingredients used in the "one-pot" process with a limited knowledge of what is actually happening in the reaction solution. METHODS: Time-resolved electrospray ionization mass spectrometry (ESI-MS) was developed to monitor the dynamic solution speciation changes occurred in the reaction mixtures ({SiW 12-x } (x = 1-3) + NaVO 3 ) against reaction time. The reactions were conducted as normal, with 2 μL aliquots removed at specific time intervals during the reaction. The aliquots were immediately diluted with 1 mL of HPLC grade water and then analyzed by ESI-MS. As a control, solutions of each {SiW 12-x } were analyzed alongside the vanadium reactions to corroborate which fragments were due to the lacunary precursors and which were due to the reactions with sodium metavanadate. RESULTS: It was discovered that the reaction solution speciation was sensitively changed with the reaction conditions such as concentration, temperature, and reaction time. Spontaneous transformations from mono-into di-and eventually tri-substituted products ({SiW 11 V} → {SiW 10 V 2 } → {SiW 9 V 3 }) were observed for the reactions of {SiW 11 } + VO 3 À and {SiW 10 } + VO 3 À , respectively. Higher concentration and temperature definitely accelerate the transformation reaction rates whereas different molar ratios of reactants have minimal effects on changing the solution speciation in the cases studied. CONCLUSIONS: Time-resolved ESI-MS is effectively and successfully used in the monitoring of the dynamic speciation changes in the reaction mixtures consisting of lacunary POMs with transition salts. This study will provide guidance for the oriented design and controlled synthesis of POMs with novel structures. Copyright © 2016 John Wiley & Sons, Ltd.Polyoxometalates (POMs) represent a class of inorganic materials with an almost unmatched range of structure types, combined with a vast range of possible uses and physical properties from materials science to biology. [1,2] In contrast to a great range of cluster types and structural diversity of POM clusters, the synthetic method is deceptively simple and straightforward, which is called "one-pot" synthesis. The apparently simple "one-pot" reactions can hide very complex solution chemistry processes arising from the presence of multiple equlibria that depends on a multitude of factors such as pH, ionic strength, reaction time, temperature, counterions, and concentration of starting materials. [3][4][5][6][7][8][9][10][11][12][13] A barely detectable change in any given parameter can alter the solution speciation, thus affecting the outcome of the reaction. The sensitive dependence of the cluster architectures on the solution reaction as well...

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The solution chemistry and reactivity of lacunary Keggin silicotungstates monitored in real-time by a combination of mass spectrometry and electrochemistry

Cited by 16 publications

References 31 publications

Soluble Hetero‐Polyoxovanadates and Their Solution Chemistry Analyzed by Electrospray Ionization Mass Spectrometry

Soluble Hetero‐Polyoxovanadates and Their Solution Chemistry Analyzed by Electrospray Ionization Mass Spectrometry

Investigation into the mechanism of polyoxotungstates-catalyzed cyclooctene epoxidation by ESI-MS

Complex solution chemistry behind the simple “one‐pot” synthesis of vanadium‐substituted polyoxometalates unraveled by electrospray ionization mass spectrometry

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