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Olefin epoxidation by [gamma-SiW10O36(PhPO)2]4- and H2O2 occurs in hydrophobic ionic liquids (ILs), with yields and selectivity up to99%. The catalytic IL phase is recyclable. Under MW irradiation the reaction occurs with up to 200 turnovers per minute. Simultaneous cooling is instrumental for quantitative H2O2 conversion.

We present herein a combined kinetic, spectroscopic, and computational study to address the electronic and structural factors that dictate the protonation sites and equilibria of the divacant polyoxotungstate catalyst, as well as their impact on the catalysis.

Polyoxometalates (POMs) are a well-known class of discrete early transition metal-oxide nanoclusters. This class of molecular metal oxides is unmatched not only in terms of structural diversity but also in reactivity and relevance to analytical chemistry, catalysis, medicine, and nanoscience. [ 1–3 ] The integration of POMs into functional architectures and devices requires the development of methods to position, orient and integrate these nanoclusters into well-defi ned architectures, thin fi lms or mesophases. [ 4 , 5 ] In this context, we have recently reported the molecular engineering of a highly robust water oxidation electrocatalyst based upon functionalized carbon nanostructures integrating tetraruthenate polyoxometalate Ru 4 ( μ -O) 4 ( μ -OH) 2 (H 2 O) 4 [ γ -SiW 10 O 36 ] 2 10 − (Ru 4 POM). [ 6–9 ]

Water oxidation is the crucial stage in the chemical and molecular sequence of photosynthesis, designed by Nature to convert solar light into chemical energy. The artificial “off-leaf” transposition is a major goal of energy research, aiming at the continuous production of hydrogen as a solar fuel, through the photo-catalytic splitting of water. Success in this task primarily depends on the interplay of light-activated multi-electron oxidation and reduction cycles and on the invention of stable and robust water oxidation catalysts, liberating oxygen with fast rates, high quantum yield, and long-term activity. A promising perspective is herein envisaged in the molecular design of functional metal-oxide cores and composite nano-materials.

The oxygen evolving catalyst [Ru(4)(μ-OH)(2)(μ-O)(4)(H(2)O)(4)(γ-SiW(10)O(36))(2)](10-) effects H(2)O(2) dismutation at rates (k = 36.8 ± 1.4 M(-1) s(-1)), one/two order of magnitude higher compared to related tetra-substituted Cu, Fe, Mn, Ni and even Co polyoxometalates, thus providing localised oxygen gas bursts to power nano-propulsion of composite materials.

Carbon nanotubes (CNTs) are versatile nanomaterials with applications spanning from medicinal chemistry and biology, to electronics as field effect transistors or energy as fuel cells. The major drawback stems from the CNT insolubility in most of the organic and aqueous media, which severely hampers the material processability. To overcome this problem, functionalization of CNTs is generally accomplished by either covalent strategies resulting in the modification of the CNT backbone via radical reactions, fluorination, and/or cycloaddition reactions, or noncovalent protocols, exploiting multiple weak interactions (hydrophobic, van der Waals, electrostatic) with suitable reagents. Herein, we highlight that a rewarding approach includes a combination of covalent/noncovalent methods, by a tailored synthetic modification of the CNT surface with polycationic dendrimeric chains, fostering the successive decoration with a multimetallic and polyanionic water oxidation catalyst. The outcome is a hybrid nanomaterial with unperturbed CNT electrical properties, in close contact with a unique multi-electron catalyst enabling electrocatalytic water splitting with high efficiency at low overpotentials.

ESI-MS analysis provides a straightforward tool for the solution characterization of highly charged mono-lacunary Keggin-type polyoxotungstates alpha-[XW11O39](p-) (X = Si, P; p = 8, 7). Doubly and triply charged quasi-molecular ion peaks were identified on the basis of both the theoretical simulation of the isotopic cluster distributions and the fragmentation modes observed with MS/MS technique. This approach allows the characterization of the inorganic polyanions transferred into the gas-phase with associated alkali metal cations (Li+, Na+). Indeed, the ESI-MS spectrum was found to be dependent on the counterion nature and on the initial concentration of the polyoxotungstate. While lithium salts at millimolar concentration represent the best choice for the analytical protocol, upon dilution the inorganic structure rearranges to a saturated Keggin dodecametalate complex. This phenomenon is induced by the electrospray ionization process and was exploited to produce gas-phase ions of monosubstituted species formed. through incorporation of molybdenum and vanadium into the polyoxotungstate framework. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).

A detailed photophysical investigation of the photocatalytic water oxidation system based on the tetraruthenium polyoxometalate [Ru4(μ-O)4(μ–OH)2(H2O)4(γ-SiW10O36)2]10– (1) as the catalyst, the tetranuclear ruthenium dendrimer [Ru{(μ-2,3-dpp)Ru(bpy)2}3]8+ (2) as the light-harvesting photosensitizer, and persulfate (S2O82–) as the sacrificial electron acceptor has shown that the water oxidation mechanism proceeds through an unusual, “anti-biomimetic” pathway: The first photochemical event is indeed a reductive quenching of the excited photosensitizer by the catalyst, followed by electron scavenging by the sacrificial electron acceptor, both occurring on the picosecond time scale within ion-paired species. As an unprecedented photoreaction mechanism for molecular water oxidation systems, these results suggest a new way to combine photosensitizers and catalysts, taking advantage of suitable chemical interactions and alternative photoinduced processes for the construction of efficient water-splitting devices.

In yeast, the protein kinase Gin4 locally controls plasma membrane lipid asymmetry, which is necessary for optimal cytokinesis., Plasma membrane function requires distinct leaflet lipid compositions. Two of the P-type ATPases (flippases) in yeast, Dnf1 and Dnf2, translocate aminoglycerophospholipids from the outer to the inner leaflet, stimulated via phosphorylation by cortically localized protein kinase Fpk1. By monitoring Fpk1 activity in vivo, we found that Fpk1 was hyperactive in cells lacking Gin4, a protein kinase previously implicated in septin collar assembly. Gin4 colocalized with Fpk1 at the cortical site of future bud emergence and phosphorylated Fpk1 at multiple sites, which we mapped. As judged by biochemical and phenotypic criteria, a mutant (Fpk111A), in which 11 sites were mutated to Ala, was hyperactive, causing increased inward transport of phosphatidylethanolamine. Thus, Gin4 is a negative regulator of Fpk1 and therefore an indirect negative regulator of flippase function. Moreover, we found that decreasing flippase function rescued the growth deficiency of four different cytokinesis mutants, which suggests that the primary function of Gin4 is highly localized control of membrane lipid asymmetry and is necessary for optimal cytokinesis.

The increasing global energy demand has stimulated great recent efforts in investigating new solutions for artificial photosynthesis, a potential source of clean and renewable solar fuel. In particular, according to the generally accepted modular approach aimed at optimising separately the different compartments of the entire process, many studies have focused on the development of catalytic systems for water oxidation to oxygen. While in recent years there have been many reports on new catalytic systems, the mechanism and the active intermediates operating the catalysis have been less investigated. Well-defined, molecular catalysts, constituted by transition metals stabilised by a suitable ligand pool, could help in solving this aspect. However, in some cases molecular species have been shown to evolve to active metal oxides that constitute the other side of this catalysis dichotomy. In this paper, we address the evolution of tetracobalt(iii) cubanes, stabilised by a pyridine/acetate ligand pool, to active species that perform water oxidation to oxygen. Primary evolution of the cubane in aqueous solution is likely initiated by removal of an acetate bridge, opening the coordination sphere of the cobalt centres. This cobalt derivative, where the pristine ligands still impact on the reactivity, shows enhanced electron transfer rates to Ru(bpy)33+(hole scavenging) within a photocatalytic cycle with Ru(bpy)32+as the photosensitiser and S2O82−as the electron sink. A more accentuated evolution occurs under continuous irradiation, where Electron Paramagnetic Resonance (EPR) spectroscopy reveals the formation of Co(ii) intermediates, likely contributing to the catalytic process that evolves oxygen. All together, these results confirm the relevant effect of molecular species, in particular in fostering the rate of the electron transfer processes involved in light activated cycles, pivotal in the design of a photoactive device.

Os resíduos sólidos urbanos são um dos principais problemas na atualidade, e a sua falta de gerenciamento está associada com uma administração municipal precária, como também pela falta de cobrança e incentivo da população com a busca da implantação de um sistema de coleta seletiva. Portanto, o presente trabalho teve como objetivo analisar a percepção ambiental dos moradores da cidade de Iomerê de Santa Catarina, quanto à possibilidade da implantação de um sistema de coleta seletiva no município. Para a realização deste trabalho, foi aplicado um questionário com 10 perguntas sobre a implantação do sistema de coleta seletiva, como também sobre os processos de gestão dos resíduos sólidos urbanos em 79 residências do município, cobrindo 20% da economia de Iomerê. O estudo mostrou que os moradores são favoráveis a implantação do sistema de coleta seletiva no município de Iomerê/SC, porém é necessária a aplicação de campanhas de educação ambiental voltada para o processo de gestão dos resíduos, devido à falta de conhecimento dos moradores sobre o processo de gerenciamento dos resíduos. A B S T R A C TUrban solid waste is one of the main problems today, and its lack of management is associated with a precarious municipal administration, as well as the lack of collection and incentive of the population with the search of the implantation of a system of selective collection. Therefore, the present work aimed to analyze the environmental perception of the residents of the city of Iomerê de Santa Catarina, regarding the possibility of implementing a selective collection system in the municipality. For the accomplishment of this work, a questionnaire with 10 questions about the implementation of the selective collection system was applied, as well as the processes of solid urban waste management in 79 residences of the municipality, covering 20% of the Iomerê economy. The study showed that the residents are favors to the implementation of the selective collection system in the city of Iomerê/SC, but it is necessary to apply environmental education campaigns focused on the waste management process, due to the lack of knowledge of the residents about the Process of waste management.Keywords: environmental education. environmental perception. selective collection system.

Molecular polyoxometalates with one embedded ruthenium center, with general formula [Ru(II/III)(DMSO)XW11O39](n-) (X = P, Si; n = 4-6), are readily synthesized in gram scale under microwave irradiation by a flash hydrothermal protocol. These nanodimensional and polyanionic complexes enable aerobic oxygenation in water. Catalytic oxygen transfer to dimethylsulfoxide (DMSO) yielding the corresponding sulfone (DMSO2 ) has been investigated with a combined kinetic, spectroscopic and computational approach addressing: (i ) the Ru(III) catalyst resting state; (ii ) the bimolecular event dictating its transformation in the rate-determining step; (iii ) its aerobic evolution to a high-valent ruthenium oxene species; (iv ) the terminal fate to diamagnetic dimers. This pathway is reminiscent of natural heme systems and of bioinspired artificial porphyrins. The in silico characterization of a key bis-Ru(IV)-μ-peroxo-POM dimeric intermediate has been accessed by density functional theory. This observation indicates a new landmark for tracing POM-based manifolds for multiredox oxygen reduction/activation, where metal-centered oxygenated species play a pivotal role.

The functional core of oxygenic photosynthesis is in charge of catalytic water oxidation by a multi-redox Mn(III)/Mn(IV) manifold that evolves through five electronic states (S(i), where i=0-4). The synthetic model system of this catalytic cycle and of its S0→S4 intermediates is the expected turning point for artificial photosynthesis. The tetramanganese-substituted tungstosilicate [Mn(III)3Mn(IV)O3(CH3COO)3(A-α-SiW9O34)](6-)(Mn4POM) offers an unprecedented mimicry of the natural system in its reduced S0 state; it features a hybrid organic-inorganic coordination sphere and is anchored on a polyoxotungstate. Evidence for its photosynthetic properties when combined with [Ru(bpy)3](2+) and S2O8(2-) is obtained by nanosecond laser flash photolysis; its S0→S1 transition within milliseconds and multiple-hole-accumulating properties were studied. Photocatalytic oxygen evolution is achieved in a buffered medium (pH 5) with a quantum efficiency of 1.7%.

Solid state and solution evidence confirms the embedding of an adamantane-like, Ru4O6 fragment by the divacant, gamma-decatungstosilicate ligand. The resulting complex catalyzes water oxidation to oxygen with TON up to 500 and TOF450 h-1.

Microwave irradiation for 15 minutes allowed the highly selective hydrothermal synthesis of the diamagnetic, air-stable oxidation catalyst [PW11O39RuII(DMSO)]5–, as confirmed by 1H, 31P, 99Ru and 183W NMR techniques.

The functional core of oxygenic photosynthesis is in charge of catalytic water oxidation by a multi-redox Mn-III/Mn-IV manifold that evolves through five electronic states (S-i, where i=0-4). The synthetic model system of this catalytic cycle and of its S0S4 intermediates is the expected turning point for artificial photosynthesis. The tetramanganese-substituted tungstosilicate [(Mn3MnO3)-Mn-III-O-IV(CH3COO)(3)(A--SiW9O34)](6-) (Mn4POM) offers an unprecedented mimicry of the natural system in its reduced S(0)state; it features a hybrid organic-inorganic coordination sphere and is anchored on a polyoxotungstate. Evidence for its photosynthetic properties when combined with [Ru(bpy)(3)](2+) and S2O82- is obtained by nanosecond laser flash photolysis; its S0S1 transition within milliseconds and multiple-hole-accumulating properties were studied. Photocatalytic oxygen evolution is achieved in a buffered medium (pH5) with a quantum efficiency of 1.7%.

Among molecular water oxidation catalysts (WOCs), those featuring a reactive set of four multi-redox transition metals can leverage an extraordinary interplay of electronic and structural properties. These are of particular interest, owing to their close structural, and possibly functional, relationship to the oxygen evolving complex of natural photosynthesis. In this review, special attention is given to two classes of tetrametallic molecular WOCs: (i) M4O4 cubane-type structures stabilized by simple organic ligands, and (ii) systems in which a tetranuclear metal core is stabilized by coordination of two polyoxometalate (POM) ligands. Recent work in this rapidly evolving field is reviewed, with particular emphasis on photocatalytic aspects. Special attention is given to studies addressing the mechanistic complexity of these systems, sometimes overlooked in the rush for oxygen evolving performance. The complementary role of molecular WOCs and their relationship with bulk oxides and heterogeneous catalysis are discussed.

A salophen cobalt(II) complex enables water oxidation at neutral pH in photoactivated sacrificial cycles under visible light, thus confirming the high appeal of earth abundant single site catalysis for artificial photosynthesis.

New progress towards artificial photosynthetic methods and solar fuels will depend on the discovery of highly robust multi-electron catalysts and materials enabling light-activated water splitting with high quantum efficiency and low overpotential, thus mimicking the natural process.

We describe a solution-phase sensor of lipid-protein binding based on localized surface plasmon resonance (LSPR) of silver nanocubes. When silica-coated nanocubes are mixed in a suspension of lipid vesicles, supported membranes spontaneously assemble on their surfaces. Using a standard laboratory spectrophotometer, we calibrated the LSPR peak shift due to protein binding to the membrane surface and then characterized the lipid-binding specificity of a pleckstrin homology domain protein.

The morphogenesis-related NDR kinase (MOR) pathway regulates morphogenesis in fungi. In spite of the high conservation of its components, impairing their functions results in highly divergent cellular responses depending on the fungal species. The reasons for such differences are unclear. Here we propose that the species-specific connections between cell cycle regulation and the MOR pathway could be partly responsible for these divergences. We based our conclusion on the characterization of the MOR pathway in the fungus Ustilago maydis. Each gene that encodes proteins of this pathway in U. maydis was deleted. All mutants exhibited a constitutive hyperpolarized growth, contrasting with the loss of polarity observed in other fungi. Using a conditional allele of the central NDR kinase Ukc1, we found that impairing MOR function resulted in a prolonged G2 phase. This cell cycle delay appears to be the consequence of an increase in Cdk1 inhibitory phosphorylation. Strikingly, prevention of the inhibitory Cdk1 phosphorylation abolished the hyperpolarized growth associated with MOR pathway depletion. We found that the prolonged G2 phase resulted in higher levels of expression of crk1, a conserved kinase that promotes polar growth in U. maydis. Deletion of crk1 also abolished the dramatic activation of polar growth in cells lacking the MOR pathway. Taken together, our results suggest that Cdk1 inhibitory phosphorylation may act as an integrator of signaling cascades regulating fungal morphogenesis and that the distinct morphological response observed in U. maydis upon impairment of the MOR pathway could be due to a cell cycle deregulation.

Isostructural cubane-shaped catalysts [Co(III)(4)(μ-O)(4)(μ-CH(3)COO)(4)(p-NC(5)H(4)X)(4)], 1-X (X = H, Me, t-Bu, OMe, Br, COOMe, CN), enable water oxidation under dark and illuminated conditions, where the primary step of photoinduced electron transfer obeys to Hammett linear free energy relationship behavior. Ligand design and catalyst optimization are instrumental for sustained O(2) productivity with quantum efficiency up to 80% at λ400 nm, thus opening a new perspective for in vitro molecular photosynthesis.