Polyoxometalates adsorbed on metallic surfaces: immediate reduction of [SiW12O40]4− on Ag(100)

Aparicio-Anglès, Xavier; Miró, Pere; Clotet, Anna; Bo, Carles; Poblet, Josep M.

doi:10.1039/c2sc20210g

Cited by 31 publications

(37 citation statements)

References 66 publications

(70 reference statements)

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“…A lamellar structure with a spacing of 3.2 nm was calculated from equidistant diffraction peaks at 2q = 2.76, 5.57, 8.40, and 11.268, which is in perfect agreement with the substructure observed in the TEM image (Figure 1 d). This value is www.chemeurj.org much smaller than the ideal packing of (DODA) 2 A C H T U N G T R E N N U N G [Mo 6 O 19 ] in sandwich structure, obtained by combining the diameter of [Mo 6 O 19 ] 2À cluster (ca. 0.8 nm) and the length of two DODA cations (ca.…”

Section: Resultsmentioning

confidence: 87%

“…Helical self-assembled morphology and structure: The POM complex used in this study was prepared by counterion exchange of Lindqvist-type cluster (TBA) 2 A C H T U N G T R E N N U N G [Mo 6 O 19 ] (TBA= tetrabutylammonium) with an excess of dioctadecyldimeth-A C H T U N G T R E N N U N G ylA C H T U N G T R E N N U N G ammonium (DODA) bearing two long alkyl chains in acetonitrile (Supporting Information, Figure S1). The chemical composition of (DODA) 2 A C H T U N G T R E N N U N G [Mo 6 O 19 ] product was identified by 1 H NMR and IR spectroscopy, mass spectrometry (Support- 6 O 19 ] with a symmetrical linear structure was prepared conveniently by replacing the tetrabutylammonium (TBA) counterions of Lindquist-type cluster (TBA) 2 -…”

Section: Resultsmentioning

confidence: 99%

“…[11] Normally, the hydrophobic force and interfacial tension drive microphase segregation, leading to self-assembly of amphiphilic POM-based complexes. Interestingly, (DODA) 2 A C H T U N G T R E N N U N G [Mo 6 O 19 ] does not form a symmetrical assembled morphology; instead, helical striplike self-assemblies are found in dichloromethane/propanol (4:1), as revealed by scanning electron microscopy (SEM; see Figure 1 a). The average helical pitch of these strips of about 1 mm indicates that the complexes are arranged next to each other with a very slight twist.…”

Section: Resultsmentioning

confidence: 99%

“…Energy-dispersive X-ray (EDX) spectroscopic analysis showed the existence of carbon and molybdenum in the same helical strips, that is, the assembly is composed of the organic-inorganic hybrid complex (Supporting Information, Figure S7). Owing to the absence of chiral centers in (DODA) 2 A C H T U N G T R E N N U N G [Mo 6 O 19 ], both leftand right-handed helices are present (Supporting Information, Figure S8). Racemic mixtures resulting from equal amounts of each helix could be confirmed by the absence of a Cotton effect in the circular dichroism (CD) spectrum (Supporting Information, Figure S9).…”

Section: Resultsmentioning

confidence: 99%

“…[5c] Reversible change between spherical and rodlike micelles of an amphiphilic hybrid POM was performed by controlling the redox states by an electrochemical method. [5d] Besides the variety of topologies and chemical compositions, the unchanged framework during redox reactions, [6] reversible photo-and electrochromism, [7] and catalytic activity [8] make POMs a versatile basis for applicable self-assembled materials.…”

Section: Introductionmentioning

confidence: 99%

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Redox‐Controlled Helical Self‐Assembly of a Polyoxometalate Complex

Zhang

et al. 2013

Chemistry A European J

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Polyoxometalate (POM) complex (DODA)₂[Mo₆O₁₉] with a symmetrical linear structure was prepared conveniently by replacing the tetrabutylammonium (TBA) counterions of Lindquist-type cluster (TBA)2 [Mo₆O₁₉] with cationic surfactant dioctadecyldimethylammonium (DODA). A helical self-assembled structure of the complex was formed in dichloromethane/propanol. The dynamically reversible transformation between helical and spherical assemblies on alternate UV irradiation and H₂O₂ oxidation was characterized by SEM, TEM, and UV/Vis studies. The redox-controlled morphology change is modulated by variation of the electrostatic interactions between the inorganic polyanion and the organic cation DODA through controlling the redox properties of the POM component, as shown by the XRD, X-ray photoelectron spectroscopic, and ¹H NMR measurements. The strategy applied herein is a unique example of targeted smart and helical assembly of POM complexes.

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Section: Resultsmentioning

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Redox‐Controlled Helical Self‐Assembly of a Polyoxometalate Complex

Zhang

et al. 2013

Chemistry A European J

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Polyoxometalates on Functional Substrates: Concepts, Synergies, and Future Perspectives

et al. 2020

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POMs were studied as heterogeneous acid catalysts and oxidation catalysts. However, this approach is often affected by low specific surface areas, leading to reduced reactivity. [10] Later studies, therefore, pioneered the immobilization of POMs on high surfacearea substrates including porous silica and other metal oxides, [10] as well as more advanced materials such as carbon nanostructures [11] and metal-organic frameworks (MOFs). [9] This strategy can enable maximized exposure of the individual POM molecules to the reaction environment, and in addition, allows for facile separation by filtration or centrifugation. [12] While early studies on POM immobilization used heterogeneous supports for mechanical stabilization and maximized surface-area, more recent studies have moved toward added properties introduced by the support. These include light-absorption and charge transport by semiconductors (TiO 2 , CdSe, etc.), electrical conductivity (by carbons, metals, conductive polymers) as well as specific POM binding sites, as introduced in MOFs and organofunctionalized supports. Many contemporary studies in this field share a common interest in exploring the synergism between POM and substrate to tune and optimize reactivity and stability of the composite. The concept has been theoretically and experimentally described several decades ago as the so-called "microenvironment effect" (electronic charge enhancement) where entrapment of POM species in a 3D matrix has been shown to induce huge improvement of their electrocatalytic activity. [13][14][15] However, to-date, the understanding of the fundamental processes which govern synergism of POM-substrate interactions is still in its infancy, as mole cular-level understanding of these complex processes by experiment or theory is far from trivial. This is due to the vast number of materials combinations, which are currently studied, and is further complicated by the often unknown chemical structures of the POM-substrate interface which make theoretical studies difficult. Also, in situ/operando studies of these materials are still challenging, and instrumentational approaches to address these issues are still being developed and not widely available. Most current experimental studies, therefore, focus on macroscopic reactivity, while providing less insight into the underlying causes of the processes observed.This Progress Report aims at raising awareness of the vast benefits of exploring this under-researched area to enable full use of POM-substrate interactions including charge and energy transfer, band-gap, and frontier orbital alignment as well as interface design for stability and reactivity. These fundamental concepts can affect both the thermodynamics as well as the kinetics of the chemical processes studied so that new reactivity can be tailored by understanding of the interactions between POM and substrate. Given the fast-paced progress in the synthesis, application, and characterization of this materials class, this Progress Report will serve as a focal point for ...

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Preparation, characterization and heterogeneous catalytic applications of GO/Fe₃O₄/HPW nanocomposite in chemoselective and green oxidation of alcohols with aqueous H₂O₂

Darvishi

Amani

Rezaei

2018

Applied Organom Chemis

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Fe 3 O 4 /HPW) was prepared by linking amino-functionalized Fe 3 O 4 nanoparticles (Fe 3 O 4 -NH 2 ) on the graphene oxide (GO), and then grafting 12tungstophosphoric acid (H 3 PW 12 O 40 ) on the graphene oxide-magnetite hybrid (GO-Fe 3 O 4 -NH 2 ). The obtained GO/Fe 3 O 4 /HPW nanocomposite was well characterized with different techniques such as FT-IR, TEM, SEM, XRD, EDX, TGA-DTA, AGFM, ICP and BET measurements. The used techniques showed that the graphene oxide layers were well prepared and the various stages of preparation of the GO/Fe 3 O 4 /HPW nanocomposites successfully completed. This new nanocomposite displayed excellent performance as a heterogeneous catalyst in the oxidation of alcohols with H 2 O 2 . The as-prepared GO/Fe 3 O 4 / HPW catalyst was more stable and recyclable at least five times without significantly reducing its catalytic activity.

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Polyoxometalates adsorbed on metallic surfaces: immediate reduction of [SiW12O40]4− on Ag(100)

Cited by 31 publications

References 66 publications

Redox‐Controlled Helical Self‐Assembly of a Polyoxometalate Complex

Redox‐Controlled Helical Self‐Assembly of a Polyoxometalate Complex

Polyoxometalates on Functional Substrates: Concepts, Synergies, and Future Perspectives

Preparation, characterization and heterogeneous catalytic applications of GO/Fe₃O₄/HPW nanocomposite in chemoselective and green oxidation of alcohols with aqueous H₂O₂

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Polyoxometalates adsorbed on metallic surfaces: immediate reduction of [SiW12O40]4− on Ag(100)

Cited by 31 publications

References 66 publications

Redox‐Controlled Helical Self‐Assembly of a Polyoxometalate Complex

Redox‐Controlled Helical Self‐Assembly of a Polyoxometalate Complex

Polyoxometalates on Functional Substrates: Concepts, Synergies, and Future Perspectives

Preparation, characterization and heterogeneous catalytic applications of GO/Fe3O4/HPW nanocomposite in chemoselective and green oxidation of alcohols with aqueous H2O2

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Preparation, characterization and heterogeneous catalytic applications of GO/Fe₃O₄/HPW nanocomposite in chemoselective and green oxidation of alcohols with aqueous H₂O₂