Hybrid Polyoxometalates: Keggin and Dawson Silyl Derivatives as Versatile Platforms

Matt, Benjamin; Renaudineau, Séverine; Chamoreau, Lise‐Marie; Afonso, Carlos; Izzet, Guillaume; Proust, Anna

doi:10.1021/jo102546v

Cited by 65 publications

(66 citation statements)

References 25 publications

(59 reference statements)

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“…61 The remaining cavity possesses highly reactive oxygen atoms and thus, it can be filled with diverse organic ligands (e.g., compounds with organostannyl, 62 between KPOM-COOH and BPOSS-NH 2 /CPOSS-NH 2 at elevated temperatures in a mixed solvent of THF/acetonitrile (v/v = 1/1) (Schemes 1a and 1b). On the other hand, the highly efficient "thiol-Michael addition" reaction 67 between thiol groups and maleimidyl groups, which has been widely used for modular syntheses of hybrid materials and modifications of biomacromolecules with high efficiency under mild reaction conditions, 68 was used to prepare KPOM-2BPOSS (Scheme 1c).…”

Section: Resultsmentioning

confidence: 99%

Manipulation of Self-Assembled Nanostructure Dimensions in Molecular Janus Particles

et al. 2016

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The ability to manipulate self-assembly of molecular building blocks is the key to achieving precise "bottom-up" fabrications of desired nanostructures. Herein, we report a rational design, facile synthesis, and self-assembly of a series of molecular Janus particles (MJPs) constructed by chemically linking α-Keggin-type polyoxometalate (POM) nanoclusters with functionalized polyhedral oligomeric silsesquioxane (POSS) cages. Diverse nanostructures were obtained by tuning secondary interactions among the building blocks and solvents via three factors: solvent polarity, surface functionality of POSS derivatives, and molecular topology. Self-assembled morphologies of KPOM-BPOSS (B denotes isobutyl groups) were found dependent on solvent polarity. In acetonitrile/water mixtures with a high dielectric constant, colloidal nanoparticles with nanophase-separated internal lamellar structures quickly formed, which gradually turned into one-dimensional nanobelt crystals upon aging, while stacked crystalline lamellae were dominantly observed in less polar methanol/chloroform solutions. When the crystallizable BPOSS was replaced with noncrystallizable cyclohexyl-functionalized CPOSS, the resulting KPOM-CPOSS also formed colloidal spheres; however, it failed to further evolve into crystalline nanobelt structures. In less polar solvents, KPOM-CPOSS crystallized into isolated two-dimensional nanosheets, which were composed of two inner crystalline layers of Keggin POM covered by two monolayers of amorphous CPOSS. In contrast, self-assembly of KPOM-2BPOSS was dominated by crystallization of the BPOSS cages, which was hardly sensitive to solvent polarity. The BPOSS cages formed the crystalline inner bilayer, sandwiched by two outer layers of Keggin POM clusters. These results illustrate a rational strategy to purposely fabricate self-assembled nanostructures with diverse dimensionality from MJPs with controlled molecular composition and topology.

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Section: Resultsmentioning

confidence: 99%

Manipulation of Self-Assembled Nanostructure Dimensions in Molecular Janus Particles

et al. 2016

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“…Indeed, in classical donor-acceptor (D-A) systems, the electron acceptor, once reduced, potentially becomes an electron donor and often displays lightabsorbing properties. Thus it may act, in a subsequent light-driven process, as a deleterious 47,48 In the previously mentioned study, transient absorptions measurements only allowed for the characterization of the first photo-induced electron transfer. Charge photo-accumulation studies can be achieved in the presence of an additional electron donor in the solution that can irreversibly quench the charge separation state, regenerate the initial state of the photosensitizer and make a second photo-induced process possible.…”

mentioning

confidence: 99%

“…The kinetics of charge separation and charge recombination in these reported POM-[Ir] hybrids were correlated to the redox potential of the POM with the fastest electron transfer rates (both charge separation and charge recombination) observed for the POMs that are the most easily reduced. 47,48 In the previously mentioned study, transient absorptions measurements only allowed for the characterization of the first photo-induced electron transfer. Charge photo-accumulation studies can be achieved in the presence of an additional electron donor in the solution that can irreversibly quench the charge separation state, regenerate the initial state of the photosensitizer and make a second photo-induced process possible.…”

mentioning

confidence: 99%

Charge photo-accumulation and photocatalytic hydrogen evolution under visible light at an iridium(iii)-photosensitized polyoxotungstate

Matt

Fize

Moussa

et al. 2013

Energy Environ. Sci.

145

115

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Steady-state irradiation under visible light of a covalent Ir(III)-photosensitized polyoxotungstate is reported. In the presence of a sacrificial electron donor, the photolysis leads to the very efficient photoreduction of the polyoxometalate. Successive formation of the one-electron and two-electron reduced species, which are unambiguously identified by comparison with spectroelectrochemical measurements, is observed with a significantly faster rate reaction for the formation of the oneelectron reduced species. The kinetics of the photoreduction, which are correlated to the reduction potentials of the polyoxometalate (POM), can be finely tuned by the presence of an acid. Indeed light-driven formation of the two-electron reduced POM is considerably facilitated in the presence of acetic acid. The system is also able to perform photocatalytic hydrogen production under visible light without significant loss of performance over more than 1 week of continuous photolysis and displays higher photocatalytic efficiency than the related multi-component system, outlining the decisive effect of the covalent bonding between the POM and the photosensitizer. This functional and modular system constitutes a promising step for the development of charge photoaccumulation devices and subsequent photoelectrocatalysts for artificial photosynthesis.Photoconversion of light into chemical fuels is emerging as a major scientific challenge. [1][2][3][4] In the past decades, molecular approaches have mostly focused on one hand on the design of photosensitive systems displaying long-lived photo-induced charge separation states to permit further electron transfers 5-10 and, on the other hand, on catalysts able to use these photogenerated charges for achieving either oxygen [11][12][13][14][15][16][17][18] or hydrogen evolution. [19][20][21][22][23][24] As these two reactions are multi-electronic processes while photosensitizers deliver electrons and holes sequentially, the charges need to be directed to a charge accumulation site. 25 However, only a few molecular photoactive systems with a designed charge accumulation site have been described so far. [26][27][28][29][30] Another requirement is crucial for efficient charge accumulation in such systems: when partially filled, the reservoir should not interfere with the photoactive moiety. Indeed, in classical donor-acceptor (D-A) systems, the electron acceptor, once reduced, potentially becomes an electron donor and often displays lightabsorbing properties. Thus it may act, in a subsequent light-driven process, as a deleterious 47,48 In the previously mentioned study, transient absorptions measurements only allowed for the characterization of the first photo-induced electron transfer. Charge photo-accumulation studies can be achieved in the presence of an additional electron donor in the solution that can irreversibly quench the charge separation state, regenerate the initial state of the photosensitizer and make a second photo-induced process possible. We herein provide unprecedente...

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“…They are obtained as globular and ellipsoidal clusters from tungsten oxides with encapsulated P atoms, where the siloxane fragments in these compounds act as units that close the polyhedron ( Fig. 26; 66 [104], 67 [105], 68 [106], 69 [107], 70 [108]). The common structural feature of these W-PHMSs is the presence of planes formed by W-O-W units, which are perpendicular to the major axis of the ellipsoid.…”

Section: [101]mentioning

confidence: 99%

Modern concepts and methods in the chemistry of polyhedral metallasiloxanes

Levitsky

Bilyachenko

2016

Coordination Chemistry Reviews

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Hybrid Polyoxometalates: Keggin and Dawson Silyl Derivatives as Versatile Platforms

Cited by 65 publications

References 25 publications

Manipulation of Self-Assembled Nanostructure Dimensions in Molecular Janus Particles

Manipulation of Self-Assembled Nanostructure Dimensions in Molecular Janus Particles

Charge photo-accumulation and photocatalytic hydrogen evolution under visible light at an iridium(iii)-photosensitized polyoxotungstate

Modern concepts and methods in the chemistry of polyhedral metallasiloxanes

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