Open AccessArticle
The Role of Anisotropic Exchange in Single Molecule Magnets: A CASSCF/NEVPT2 Study of the Fe4 SMM Building Block [Fe2(OCH3)2(dbm)4] Dimer
Inorganics 2016, 4(4), 28; doi:10.3390/inorganics4040028 -
Abstract
The rationalisation of single molecule magnets’ (SMMs) magnetic properties by quantum mechanical approaches represents a major task in the field of the Molecular Magnetism. The fundamental interpretative key of molecular magnetism is the phenomenological Spin Hamiltonian and the understanding of the role [...] Read more.
The rationalisation of single molecule magnets’ (SMMs) magnetic properties by quantum mechanical approaches represents a major task in the field of the Molecular Magnetism. The fundamental interpretative key of molecular magnetism is the phenomenological Spin Hamiltonian and the understanding of the role of its different terms by electronic structure calculations is expected to steer the rational design of new and more performing SMMs. This paper deals with the ab initio calculation of isotropic and anisotropic exchange contributions in the Fe(III) dimer [Fe2(OCH3)2(dbm)4]. This system represents the building block of one of the most studied Single Molecule Magnets ([Fe4RC(CH2O)3)2(dpm)6] where R can be an aliphatic chain or a phenyl group just to name the most common functionalization groups) and its relatively reduced size allows the use of a high computational level of theory. Calculations were performed using CASSCF and NEVPT2 approaches on the X-ray geometry as assessment of the computational protocol, which has then be used to evinced the importance of the outer coordination shell nature through organic ligand modelization. Magneto-structural correlations as function of internal degrees of freedom for isotropic and anisotropic exchange contributions are also presented, outlining, for the first time, the extremely rapidly changing nature of the anisotropic exchange coupling. Full article
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Open AccessArticle
Optical Properties of Heavily Fluorinated Lanthanide Tris β-Diketonate Phosphine Oxide Adducts
Inorganics 2016, 4(3), 27; doi:10.3390/inorganics4030027 (registering DOI) -
Abstract
The construction of lanthanide(III) chelates that exhibit superior photophysical properties holds great importance in biological and materials science. One strategy to increase the luminescence properties of lanthanide(III) chelates is to hinder competitive non-radiative decay processes through perfluorination of the chelating ligands. Here, [...] Read more.
The construction of lanthanide(III) chelates that exhibit superior photophysical properties holds great importance in biological and materials science. One strategy to increase the luminescence properties of lanthanide(III) chelates is to hinder competitive non-radiative decay processes through perfluorination of the chelating ligands. Here, the synthesis of two families of heavily fluorinated lanthanide(III) β-diketonate complexes bearing monodentate perfluorinated tris phenyl phosphine oxide ligands have been prepared through a facile one pot reaction [Ln(hfac)3{(ArF)3PO}(H2O)] and [Ln(F7-acac)3{(ArF)3PO}2] (where Ln = Sm3+, Eu3+, Tb3+, Er3+ and Yb3+). Single crystal X-ray diffraction analysis in combination with photophysical studies have been performed to investigate the factors responsible for the differences in the luminescence lifetimes and intrinsic quantum yields of the complexes. Replacement of both bound H2O and C–H oscillators in the ligand backbone has a dramatic effect on the photophysical properties of the complexes, particularly for the near infra-red emitting ion Yb3+, where a five fold increase in luminescence lifetime and quantum yield is observed. The complexes [Sm(hfac)3{(ArF)3PO}(H2O)] (1), [Yb(hfac)3{(ArF)3PO}(H2O)] (5), [Sm(F7-acac)3{(ArF)3PO}2] (6) and [Yb(F7-acac)3{(ArF)3PO}2] (10) exhibit unusually long luminescence lifetimes and attractive intrinsic quantum yields of emission in fluid solution (ΦLn = 3.4% (1); 1.4% (10)) and in the solid state (ΦLn = 8.5% (1); 2.0% (5); 26% (6); 11% (10)), which are amongst the largest values for this class of compounds to date. Full article
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Open AccessCommunication
Zirconium-Catalyzed Alkene Hydrophosphination and Dehydrocoupling with an Air-Stable, Fluorescent Primary Phosphine
Inorganics 2016, 4(3), 26; doi:10.3390/inorganics4030026 -
Abstract
Zirconium-catalyzed alkene hydrophosphination and dehydrocoupling with an air-stable, fluorescent primary phosphine 8-[(4-phosphino)phenyl]-4,4-dimethyl-1,3,5,7-tetramethyl-2,6-diethyl-4-bora-3a,4a-diaza-s-indacene furnishes fluorescent phosphine products. Hydrophosphination of the fluorescent phosphine produces products with a complete selectivity for the secondary product. A key intermediate in catalysis, a zirconium [...] Read more.
Zirconium-catalyzed alkene hydrophosphination and dehydrocoupling with an air-stable, fluorescent primary phosphine 8-[(4-phosphino)phenyl]-4,4-dimethyl-1,3,5,7-tetramethyl-2,6-diethyl-4-bora-3a,4a-diaza-s-indacene furnishes fluorescent phosphine products. Hydrophosphination of the fluorescent phosphine produces products with a complete selectivity for the secondary product. A key intermediate in catalysis, a zirconium phosphido compound, was isolated. Full article
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Open AccessArticle
The Trans Influence in Unsymmetrical Pincer Palladacycles: An Experimental and Computational Study
Inorganics 2016, 4(3), 25; doi:10.3390/inorganics4030025 -
Abstract
A library of unsymmetrical SCN pincer palladacycles, [ClPd{2-pyr-6-(RSCH2)C6H3}], R = Et, Pr, Ph, p-MePh, and p-MeOPh, pyr = pyridine, has been synthesized via C–H bond activation, and used, along with PCN and N’CN unsymmetrical [...] Read more.
A library of unsymmetrical SCN pincer palladacycles, [ClPd{2-pyr-6-(RSCH2)C6H3}], R = Et, Pr, Ph, p-MePh, and p-MeOPh, pyr = pyridine, has been synthesized via C–H bond activation, and used, along with PCN and N’CN unsymmetrical pincer palladacycles previously synthesized by the authors, to determine the extent to which the trans influence is exhibited in unsymmetrical pincer palladacycles. The trans influence is quantified by analysis of structural changes in the X-ray crystal and density functional theory (DFT) optimized structures and a topological analysis of the electron density using quantum theory of atoms in molecules (QTAIM) to determine the strength of the Pd-donor atom interaction. It is found that the trans influence is controlled by the nature of the donor atom and although the substituents on the donor-ligand affect the Pd-donor atom interaction through the varied electronic and steric constraints, they do not influence the bonding of the ligand trans to it. The data indicate that the strength of the trans influence is P > S > N. Furthermore, the synthetic route to the family of SCN pincer palladacycles presented demonstrates the potential of late stage derivitization for the effective synthesis of ligands towards unsymmetrical pincer palladacycles. Full article
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Open AccessArticle
Mesoporous WN/WO3-Composite Nanosheets for the Chemiresistive Detection of NO2 at Room Temperature
Inorganics 2016, 4(3), 24; doi:10.3390/inorganics4030024 -
Abstract
Composite materials, which can optimally use the advantages of different materials, have been studied extensively. Herein, hybrid tungsten nitride and oxide (WN/WO3) composites were prepared through a simple aqueous solution route followed by nitriding in NH3, for application [...] Read more.
Composite materials, which can optimally use the advantages of different materials, have been studied extensively. Herein, hybrid tungsten nitride and oxide (WN/WO3) composites were prepared through a simple aqueous solution route followed by nitriding in NH3, for application as novel sensing materials. We found that the introduction of WN can improve the electrical properties of the composites, thus improving the gas sensing properties of the composites when compared with bare WO3. The highest sensing response was up to 21.3 for 100 ppb NO2 with a fast response time of ~50 s at room temperature, and the low detection limit was 1.28 ppb, which is far below the level that is immediately dangerous to life or health (IDLH) values (NO2: 20 ppm) defined by the U.S. National Institute for Occupational Safety and Health (NIOSH). In addition, the composites successfully lower the optimum temperature of WO3 from 300 °C to room temperature, and the composites-based sensor presents good long-term stability for NO2 of 100 ppb. Furthermore, a possible sensing mechanism is proposed. Full article
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Open AccessReview
Anion Ordering in Bichalcogenides
Inorganics 2016, 4(3), 23; doi:10.3390/inorganics4030023 -
Abstract
This review contains recent developments and new insights in the research on inorganic, crystalline compounds with two different chalcogenide ions (bichalcogenides). Anion ordering is used as a parameter to form structural dimensionalities as well as local- and global-electric polarities. The reason for [...] Read more.
This review contains recent developments and new insights in the research on inorganic, crystalline compounds with two different chalcogenide ions (bichalcogenides). Anion ordering is used as a parameter to form structural dimensionalities as well as local- and global-electric polarities. The reason for the electric polarity is that, in the heterogeneous bichalcogenide lattice, the individual bond-lengths between cations and anions are different from those in a homogeneous anion lattice. It is also shown that heteroleptic tetrahedral and octahedral coordinations offer a multitude of new crystal fields and coordinations for involved cations. This coordination diversity in bichalcogenides seems to be one way to surpass electro-chemical redox potentials: three oxidation states of a single transition metal can be stabilized, e.g., Ba15V12S34O3. A new type of disproportionation, related to coordination, is presented and results from chemical pressure on the bichalcogenide lattices of (La,Ce)CrS2O, transforming doubly [CrS3/3S2/2O1/1]3− (5+1) into singly [CrS4/2S2/3]7/3− (6+0) and [CrS4/3O2/1]11/3− (4+2) coordinations. Also, magnetic anisotropy is imposed by the anion ordering in BaCoSO, where magnetic interactions via S or O occur along two different crystallographic directions. Further, the potential of the anion lattice is discussed as a parameter for future materials design. Full article
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Open AccessArticle
Mesoporous C/CrN and C/VN Nanocomposites Obtained by One-Pot Soft-Templating Process
Inorganics 2016, 4(3), 22; doi:10.3390/inorganics4030022 -
Abstract
Nanocomposites of ordered mesoporous carbon associated with chromium nitride (CrN) or vanadium nitride (VN) nanoparticles were obtained by a simple one-pot synthesis based on the solvent evaporation induced self-assembly (EISA) process using Pluronic triblock surfactant as soft-template and a phenol-based resin (resol) [...] Read more.
Nanocomposites of ordered mesoporous carbon associated with chromium nitride (CrN) or vanadium nitride (VN) nanoparticles were obtained by a simple one-pot synthesis based on the solvent evaporation induced self-assembly (EISA) process using Pluronic triblock surfactant as soft-template and a phenol-based resin (resol) as carbon precursor. These nanocomposites were characterized by X-ray diffraction, nitrogen physisorption and Transmission Electron Microscopy (TEM) techniques. Electron tomography (or 3D-TEM) technique was particularly useful for providing direct insight on the internal architecture of C/CrN nanocomposite. Nanocomposites showed a very well organized hexagonal mesoporous carbon structure and a relatively high concentration of nanoparticles well distributed in the porous network. The chromium and vanadium nitrides/mesoporous carbon nanocomposites could have many potential applications in catalysis, Li-ion batteries, and supercapacitors. Full article
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Open AccessArticle
Silylation of Dinitrogen Catalyzed by Hydridodinitrogentris(Triphenylphosphine)Cobalt(I)
Inorganics 2016, 4(3), 21; doi:10.3390/inorganics4030021 -
Abstract
Recently, homogeneous cobalt systems were reported to catalyze the reductive silylation of dinitrogen. In this study the investigations on the silylation of dinitrogen catalyzed by CoH(PPh3)3N2 are presented. We show that in the presence of the title [...] Read more.
Recently, homogeneous cobalt systems were reported to catalyze the reductive silylation of dinitrogen. In this study the investigations on the silylation of dinitrogen catalyzed by CoH(PPh3)3N2 are presented. We show that in the presence of the title compound, the reaction of N2 with trimethylsilylchloride and sodium yields, on average, 6.7 equivalents of tris(trimethylsilyl)amine per Co atom in THF (tetrahydrofuran). The aim was to elucidate whether the active catalyst is: (a) the [Co(PPh3)3N2] anion formed after two-electron reduction of the title compound; or (b) a species formed via decomposition of CoH(PPh3)3N2 in the presence of the highly reactive substrates. Time profile, and IR and EPR spectroscopic investigations show instability of the pre-catalyst under the applied conditions which suggests that the catalytically active species is formed through in situ modification of the pre-catalyst. Full article
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Open AccessCommunication
The Viscosity and Intermolecular Interaction of Organic and Inorganic Hybrid Systems Composed of Chiral Schiff Base Ni(II), Cu(II), and Zn(II) Complexes with Long Ligands, Azobenzene, and PMMA
Inorganics 2016, 4(3), 20; doi:10.3390/inorganics4030020 -
Abstract
We have here synthesized new chiral Schiff base Ni(II), Cu(II), Zn(II) complexes (Ni, Cu, Zn) and hybrid materials with azobenzene (AZ) in polymethyl methacrylate (PMMA). Linearly polarized UV light irradiation of these hybrid materials [...] Read more.
We have here synthesized new chiral Schiff base Ni(II), Cu(II), Zn(II) complexes (Ni, Cu, Zn) and hybrid materials with azobenzene (AZ) in polymethyl methacrylate (PMMA). Linearly polarized UV light irradiation of these hybrid materials slightly increased their optical anisotropy of AZ as well as the complexes, which were measured with polarized IR and UV-Vis spectra and discussed based on TD-DFT calculations. Non-linear concentration (viscosity) dependence of PMMA solutions about artifact peaks suggested weak intermolecular interactions due to the flexibility of complexes by inserted methylene chains. Molecular modeling indicated that large spaces around complexes in PMMA resulted in easy molecular orientation (Ni > Cu > Zn) as short-term saturation of the UV light irradiation. Full article
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Open AccessCommunication
Monoanionic Tin Oligomers Featuring Sn–Sn or Sn–Pb Bonds: Synthesis and Characterization of a Tris(Triheteroarylstannyl)Stannate and -Plumbate
Inorganics 2016, 4(2), 19; doi:10.3390/inorganics4020019 -
Abstract
The reaction of the lithium tris(2-pyridyl)stannate [LiSn(2-py6OtBu)3] (py6OtBu = C5H3N-6-OtBu), 1, with the element(II) amides E{N(SiMe3)2}2 (E = Sn, Pb) afforded [...] Read more.
The reaction of the lithium tris(2-pyridyl)stannate [LiSn(2-py6OtBu)3] (py6OtBu = C5H3N-6-OtBu), 1, with the element(II) amides E{N(SiMe3)2}2 (E = Sn, Pb) afforded complexes [LiE{Sn(2-py6OtBu)3}3] for E = Sn (2) and E = Pb (3), which reveal three Sn–E bonds each. Compounds 2 and 3 have been characterized by solution NMR spectroscopy and X-ray crystallographic studies. Large 1J(119Sn–119/117Sn) as well as 1J(207Pb–119/117Sn) coupling constants confirm their structural integrity in solution. However, contrary to 2, complex 3 slowly disintegrates in solution to give elemental lead and the hexaheteroarylditin [Sn(2-py6OtBu)3]2 (4). Full article
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Open AccessArticle
Tetrapropylammonium Occlusion in Nanoaggregates of Precursor of Silicalite-1 Zeolite Studied by 1H and 13C NMR
Inorganics 2016, 4(2), 18; doi:10.3390/inorganics4020018 -
Abstract
The dynamic behavior of tetrapropylammonium (TPA) cations in the clear precursor sols for silicalite synthesis has been investigated by 1H diffusion ordered spectroscopy (DOSY), T1, T2, and T1H relaxation, as well as 1H→[...] Read more.
The dynamic behavior of tetrapropylammonium (TPA) cations in the clear precursor sols for silicalite synthesis has been investigated by 1H diffusion ordered spectroscopy (DOSY), T1, T2, and T1H relaxation, as well as 1H→13C cross polarization (CP) nuclear magnetic resonance. The DOSY NMR experiments showed the presence of strong solute–solvent interactions in concentrated sols, which are decreasing upon dilution. Similarities in dependence of diffusion coefficients with fractional power of the viscosity constant observed for nanoparticles, TPA cations and water led to the conclusion that they aggregate as anisotropic silicate-TPA particles. Relaxation studies as well as 1H→13C CP experiments provide information on dynamic properties of ethanol, water and TPA cations, which are function of silicate aggregates. The general tendency showed that the presence of silicate as oligomers and particles decreases the relaxation times, in particular T2 and T1ρH, as a consequence of involvement of these latter in ion-pairing interactions with water-solvated TPA molecules slowing down their mobility. Furthermore, from the 1H→13C CP dynamics curve profiles a change in the CP transfer regime was observed from fast (TCH << T1ρH) for solutions without silicates to moderate (TCH~T1ρH) when silicates are interacting with the TPA cations that may reflect the occlusion of TPA into flexible silicate hydrate aggregates. Full article
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Open AccessArticle
Olivine-Based Blended Compounds as Positive Electrodes for Lithium Batteries
Inorganics 2016, 4(2), 17; doi:10.3390/inorganics4020017 -
Abstract
Blended cathode materials made by mixing LiFePO4 (LFP) with LiMnPO4 (LMP) or LiNi1/3Mn1/3Co1/3O2 (NMC) that exhibit either high specific energy and high rate capability were investigated. The layered blend LMP–LFP and the physically [...] Read more.
Blended cathode materials made by mixing LiFePO4 (LFP) with LiMnPO4 (LMP) or LiNi1/3Mn1/3Co1/3O2 (NMC) that exhibit either high specific energy and high rate capability were investigated. The layered blend LMP–LFP and the physically mixed blend NMC–LFP are evaluated in terms of particle morphology and electrochemical performance. Results indicate that the LMP–LFP (66:33) blend has a better discharge rate than the LiMn1−yFeyPO4 with the same composition (y = 0.33), and NMC–LFP (70:30) delivers a remarkable stable capacity over 125 cycles. Finally, in situ voltage measurement methods were applied for the evaluation of the phase evolution of blended cathodes and gradual changes in cell behavior upon cycling. We also discuss through these examples the promising development of blends as future electrodes for new generations of Li-ion batteries. Full article
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Open AccessArticle
β,β-Isomer of Open-Wells–Dawson Polyoxometalate Containing a Tetra-Iron(III) Hydroxide Cluster: [{Fe4(H2O)(OH)5}(β,β-Si2W18O66)]9−
Inorganics 2016, 4(2), 15; doi:10.3390/inorganics4020015 -
Abstract
The β,β-isomer of open-Wells–Dawson polyoxometalate (POM) containing a tetra-iron(III) cluster, K9[{Fe4(H2O)(OH)5}(β,β-Si2W18O66)]·17H2O (potassium salt of β,β-Fe4-open), was synthesized by reacting Na9H[A-β-SiW9O[...] Read more.
The β,β-isomer of open-Wells–Dawson polyoxometalate (POM) containing a tetra-iron(III) cluster, K9[{Fe4(H2O)(OH)5}(β,β-Si2W18O66)]·17H2O (potassium salt of β,β-Fe4-open), was synthesized by reacting Na9H[A-β-SiW9O34]·23H2O with FeCl3·6H2O at pH 3, and characterized by X-ray crystallography, FTIR, elemental analysis, TG/DTA, UV–Vis, and cyclic voltammetry. X-ray crystallography revealed that the {Fe3+4(H2O)(OH)5}7+ cluster was included in the open pocket of the β,β-type open-Wells–Dawson polyanion [β,β-Si2W18O66]16− formed by the fusion of two trilacunary β-Keggin POMs, [A-β-SiW9O34]10−, via two W–O–W bonds. The β,β-open-Wells–Dawson polyanion corresponds to an open structure of the standard γ-Wells–Dawson POM. β,β-Fe4-open is the first example of the compound containing a geometrical isomer of α,α-open-Wells–Dawson structural POM. Full article
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Open AccessArticle
Synthesis, Structure, and Characterization of In10-Containing Open-Wells–Dawson Polyoxometalate
Inorganics 2016, 4(2), 16; doi:10.3390/inorganics4020016 -
Abstract
We have successfully synthesized K17{[{KIn2(μ-OH)2}(α,α-Si2W18O66)]2[In6(μ-OH)13(H2O)8]}·35H2O (potassium salt of In10-open), an open-Wells–Dawson polyoxometalate (POM) containing ten indium [...] Read more.
We have successfully synthesized K17{[{KIn2(μ-OH)2}(α,α-Si2W18O66)]2[In6(μ-OH)13(H2O)8]}·35H2O (potassium salt of In10-open), an open-Wells–Dawson polyoxometalate (POM) containing ten indium metal atoms. This novel compound was characterized by X-ray crystallography, 29Si NMR, FTIR, complete elemental analysis, and TG/DTA. X-ray crystallography results for {[{KIn2(μ-OH)2}(α,α-Si2W18O66)]2[In6(μ-OH)13(H2O)8]}17− (In10-open) revealed two open-Wells–Dawson units containing two In3+ ions and a K+ ion, [{KIn2(μ-OH)2}(α,α-Si2W18O66)]11−, connected by an In6-hydroxide cluster moiety, [In6(μ-OH)13(H2O)8]5+. In10-open is the first example of an open-Wells–Dawson POM containing a fifth-period element. Moreover, to the best of our knowledge, it exhibits the highest nuclearity among the indium-containing POMs reported to date. Full article
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Open AccessArticle
Naphthyl-Containing Organophosphonate Derivatives of Keggin-Type Polyoxotungstates
Inorganics 2016, 4(2), 14; doi:10.3390/inorganics4020014 -
Abstract
New organophosphonate derivatives of monovacant Keggin-type polyoxotungstates that contain naphthyl groups have been synthesized and characterized in both solid state and solution. Single-crystal structural analysis shows that two phosphonate groups occupy the vacant position of the lacunary cluster unit in the isostructural [...] Read more.
New organophosphonate derivatives of monovacant Keggin-type polyoxotungstates that contain naphthyl groups have been synthesized and characterized in both solid state and solution. Single-crystal structural analysis shows that two phosphonate groups occupy the vacant position of the lacunary cluster unit in the isostructural compounds [N(C4H9)4]3[H(POC11H9)2(α-HBW11O39)] (TBA-1) and [N(C4H9)4]3[H(POC11H9)2(α-SiW11O39)] (TBA-2). Liquid-solution UV–Vis transmittance and solid-state diffuse reflectance spectroscopy studies reveal the presence of a new absorption band in the visible region, the charge transfer character of which has been further confirmed by time-dependent density functional theory (TD-DFT) calculations. The latter evidence that the charge transfer process is dominated by transitions from the highest occupied molecular orbital (HOMO), localized in the aromatic ring of the organic group, to the lowest unoccupied molecular orbital (LUMO), localized in the Keggin anion. Photoluminescence studies show that the fluorescent properties of the 1-naphthylmethylphosphonate group are quenched upon its incorporation into the inorganic oxo-tungstate skeleton. The solution stability of the hybrid clusters has been evaluated by a combination of 1H-, 13C- and 31P-Nuclear Magnetic Resonance spectroscopy and Electrospray Ionization-Mass Spectrometry. The hybrid polyanion [H(POC11H9)2(α-HBW11O39)]3− (1) herein constitutes the first structurally characterized organo-p-block containing borotungstate, and hence it confirms that this strategy for the organic functionalization of polyoxometalate clusters can be applied to new platforms belonging to the family of group-13 heteropolyoxotungstates. Full article
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Open AccessReview
Synthesis, Characterization and Applications in Catalysis of Polyoxometalate/Zeolite Composites
Inorganics 2016, 4(2), 13; doi:10.3390/inorganics4020013 -
Abstract
An overview of the synthesis, characterization and catalytic applications of polyoxometalates/zeolites composites is given. The solids obtained by direct synthesis of the polyoxometalate in the presence of the zeolite are first described with their applications in catalysis. Those obtained by a direct [...] Read more.
An overview of the synthesis, characterization and catalytic applications of polyoxometalates/zeolites composites is given. The solids obtained by direct synthesis of the polyoxometalate in the presence of the zeolite are first described with their applications in catalysis. Those obtained by a direct mixing of the two components are then reviewed. In all cases, special care is taken in the localization of the polyoxometalate, inside the zeolite crystal, in mesopores or at the external surface of the crystals, as deduced from the characterization methods. Full article
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Open AccessReview
Advances in Engineered Hemoproteins that Promote Biocatalysis
Inorganics 2016, 4(2), 12; doi:10.3390/inorganics4020012 -
Abstract
Some hemoproteins have the structural robustness to withstand extraction of the heme cofactor and replacement with a heme analog. Recent reports have reignited interest and exploration in this field by demonstrating the versatility of these systems. Heme binding proteins can be utilized [...] Read more.
Some hemoproteins have the structural robustness to withstand extraction of the heme cofactor and replacement with a heme analog. Recent reports have reignited interest and exploration in this field by demonstrating the versatility of these systems. Heme binding proteins can be utilized as protein scaffolds to support heme analogs that can facilitate new reactivity by noncovalent bonding at the heme-binding site utilizing the proximal ligand for support. These substituted hemoproteins have the capability to enhance catalytic reactivity and functionality comparatively to their native forms. This review will focus on progress and recent advances of artificially engineered hemoproteins utilized as a new target for the development of biocatalysts. Full article
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Open AccessReview
Manganese and Iron Catalysts in Alkyd Paints and Coatings
Inorganics 2016, 4(2), 11; doi:10.3390/inorganics4020011 -
Abstract
Many paint, ink and coating formulations contain alkyd-based resins which cure via autoxidation mechanisms. Whilst cobalt-soaps have been used for many decades, there is a continuing and accelerating desire by paint companies to develop alternatives for the cobalt soaps, due to likely [...] Read more.
Many paint, ink and coating formulations contain alkyd-based resins which cure via autoxidation mechanisms. Whilst cobalt-soaps have been used for many decades, there is a continuing and accelerating desire by paint companies to develop alternatives for the cobalt soaps, due to likely classification as carcinogens under the REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) legislation. Alternative driers, for example manganese and iron soaps, have been applied for this purpose. However, relatively poor curing capabilities make it necessary to increase the level of metal salts to such a level that often coloring of the paint formulation occurs. More recent developments include the application of manganese and iron complexes with a variety of organic ligands. This review will discuss the chemistry of alkyd resin curing, the applications and reactions of cobalt-soaps as curing agents, and, subsequently, the paint drying aspects and mechanisms of (model) alkyd curing using manganese and iron catalysts. Full article
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Open AccessReview
Adsorption of Water on Two-Dimensional Crystals: Water/Graphene and Water/Silicatene
Inorganics 2016, 4(2), 10; doi:10.3390/inorganics4020010 -
Abstract
The adsorption of water on solid surfaces is a scientific evergreen which again recently prompted considerable attention in the materials, nano-, and surface science communities, respectively, due to conflicting evidence presented in the most highly regarded scientific journals. This mini review is [...] Read more.
The adsorption of water on solid surfaces is a scientific evergreen which again recently prompted considerable attention in the materials, nano-, and surface science communities, respectively, due to conflicting evidence presented in the most highly regarded scientific journals. This mini review is a brief and personal perspective of the current literature (and our own data) about water adsorption for two examples, namely graphene and silicatene, which are both two-dimensional (2D) crystals. Silicatene, an inorganic companion of graphene, is intriguing as it presents us with the possibility to synthesize a 2D analog to zeolites by doping this crystalline silicon film. The wettability by water and whether or not support effects of epitaxial 2D crystals are present is of concern. Regarding applications: some 2D crystals appear promising for the hydrogen evolution reaction, i.e., hydrogen generation from water; a functionalization of graphene (by oxygen/water) to graphene oxide may be interesting for metal-free catalysis; the latest highlight in this field appears to be “icephobicity”, an application related to the hydrophobicity of surfaces. Full article
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Open AccessArticle
Synthesis and Textural Characterization of Mesoporous and Meso-/Macroporous Silica Monoliths Obtained by Spinodal Decomposition
Inorganics 2016, 4(2), 9; doi:10.3390/inorganics4020009 -
Abstract
Silica monoliths featuring either mesopores or flow-through macropores and mesopores in their skeleton are prepared by combining spinodal phase separation and sol-gel condensation. The macroporous network is first generated by phase separation in acidic medium in the presence of polyethyleneoxides while mesoporosity [...] Read more.
Silica monoliths featuring either mesopores or flow-through macropores and mesopores in their skeleton are prepared by combining spinodal phase separation and sol-gel condensation. The macroporous network is first generated by phase separation in acidic medium in the presence of polyethyleneoxides while mesoporosity is engineered in a second step in alkaline medium, possibly in the presence of alkylammonium cations as surfactants. The mesoporous monoliths, also referred as aerogels, are obtained in the presence of alkylpolyethylene oxides in acidic medium without the use of supercritical drying. The impact of the experimental conditions on pore architecture of the monoliths regarding the shape, the ordering, the size and the connectivity of the mesopores is comprehensively discussed based on a critical appraisal of the different models used for textural analysis. Full article
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