Controlled growth of narrowly dispersed nanosize hexagonal MOF rods from Mn(III)-porphyrin and In(NO3)3 and their application in olefin oxidation

A new class of narrowly dispersed nanosize hexagonal MOF rods from Mn(III)-porphyrin and In(III) was obtained. The length of MOF rods was controlled by simple change of reaction times. Furthermore, the oxidation of styrene has been successfully demonstrated with Mn(III)-porphyrin MOF rods and their reusability has been also tested.     

Self-Assembled Nanomaterials Based on Complementary Sn(IV) and Zn(II)-Porphyrins,and Their Photocatalytic Degradation for Rhodamine B Dye

A series of porphyrin triads (1–6), based on the reaction of trans-dihydroxo-[5,15-bis(3-pyridyl)-10,20-bis(phenyl)porphyrinato]tin(IV) (SnP) with six different phenoxy Zn(II)-porphyrins (ZnLⁿ), was synthesized. The cooperative metal–ligand coordination of 3-pyridyl nitrogens in the SnP with the phenoxy Zn(II)-porphyrins, followed by the self-assembly process, leads to the formation of nanostructures. The red-shifts and remarkable broadening of the absorption bands in the UV–vis spectra for the triads in CHCl₃ indicate that nanoaggregates may be produced in the self-assembly process of these triads. The emission intensities of the triads were also significantly reduced due to the aggregation. Microscopic analyses of the nanostructures of the triads reveal differences due to the different substituents on the axial Zn(II)-porphyrin moieties. All these nanomaterials exhibited efficient photocatalytic performances in the degradation of rhodamine B (RhB) dye under visible light irradiation, and the degradation efficiencies of RhB in aqueous solution were observed to be 72~95% within 4 h. In addition, the efficiency of the catalyst was not impaired, showing excellent recyclability even after being applied for the degradation of RhB in up to five cycles.     

Interfacial synthesis of dendritic platinum nanoshells templated on benzene nanodroplets stabilized in water by a photocatalytic lipoporphyrin

Nanoscale metal shells have many potential uses and in some applications offer significant advantages over nanoparticles. The synthesis of platinum nanoshells using stabilized nanodroplets of benzene in water as growth templates is described; the nanodroplets are stabilized by a surfactant-like tin(IV)-porphyrin complex localized at the benzene-water interface. The porphyrin also acts as a photocatalyst that reduces the platinum complex and deposits metal onto the nanodroplets to form dendritic metal nanoshells. Below the solubility limit of benzene in water, the lipoporphyrin-stabilized nanodroplets have a reproducible number, size distribution, and surface area, which allows the thickness of the platinum shell walls to be controlled by changing the amount of platinum complex. Nanoscale platinum shells with magnetic interiors can be made by dispersing Fe3O4 nanoparticles in the benzene nanodroplets.     

Photocatalytic Hydrogen Production by the Sensitization of Sn(IV)-Porphyrin Embedded in a Nafion Matrix Coated on TiO2

Efficient utilization of visible light for photocatalytic hydrogen production is one of the most important issues to address. This report describes a facile approach to immobilize visible-light sensitizers on TiO₂ surfaces. To effectively utilize the sensitization of Sn(IV) porphyrin species for photocatalytic hydrogen production, perfluorosulfonate polymer (Nafion) matrix coated-TiO₂ was fabricated. Nafion coated-TiO₂ readily adsorbed trans-diaqua[meso-tetrakis(4-pyridinium)porphyrinato]tin(IV) cation [(TPy^HP)Sn(OH₂)₂]⁶⁺ via an ion-exchange process. The uptake of [(TPy^HP)Sn(OH₂)₂]⁶⁺ in an aqueous solution completed within 30 min, as determined by UV-vis spectroscopy. The existence of Sn(IV) porphyrin species embedded in the Nafion matrix coated on TiO₂ was confirmed by zeta potential measurements, UV-vis absorption spectroscopy, TEM combined with energy dispersive X-ray spectroscopy, and thermogravimetric analysis. Sn(IV)-porphyrin cationic species embedded in the Nafion matrix were successfully used as visible-light sensitizer for photochemical hydrogen generation. This photocatalytic system performed 45% better than the uncoated TiO₂ system. In addition, the performance at pH 7 was superior to that at pH 3 or 9. This work revealed that Nafion matrix coated-TiO₂ can efficiently produce hydrogen with a consistent performance by utilizing a freshly supplied cationic Sn(IV)-porphyrin sensitizer in a neutral solution.     

Mechanistic studies on peroxide activation by a water-soluble iron(III)-porphyrin: implications for O-O bond activation in aqueous and nonaqueous solvents

The reactions of a water-soluble iron(III)-porphyrin, [meso-tetrakis(sulfonatomesityl)porphyrinato]iron(III), [Fe(III)(tmps)] (1), with m-chloroperoxybenzoic acid (mCPBA), iodosylbenzene (PhIO), and H(2)O(2) at different pH values in aqueous methanol solutions at -35 degrees C have been studied by using stopped-flow UV/Vis spectroscopy. The nature of the porphyrin product resulting from the reactions with all three oxidants changed from the oxo-iron(IV)-porphyrin pi-cation radical [Fe(IV)(tmps(*+))(O)] (1(++)) at pH<5.5 to the oxo-iron(IV)-porphyrin [Fe(IV)(tmps)(O)] (1(+)) at pH>7.5, whereas a mixture of both species was formed in the intermediate pH range of 5.5-7.5. The observed reactivity pattern correlates with the E degrees' versus pH profile reported for 1, which reflects pH-dependent changes in the relative positions of E degrees'(Fe(IV)/Fe(III) ) and E degrees'(P(*+)/P) for metal- and porphyrin-centered oxidation, respectively. On this basis, the pH-dependent redox equilibria involving 1(++) and 1(+) are suggested to determine the nature of the final products that result from the oxidation of 1 at a given pH. The conclusions reached are extended to water-insoluble iron(III)-porphyrins on the basis of literature data concerning the electrochemical and catalytic properties of [Fe(III)(P)(X)] species in nonaqueous solvents. Implications for mechanistic studies on [Fe(P)]-catalyzed oxidation reactions are briefly addressed.     

Synthesis and structure determination from powder data of the first organically templated tin(IV) phosphate: MIL-76 or Sn3(IV)O2(H2O)(HPO4)4 x [H2N-C2H4-NH2]2.5 x [H2O]2

The first organically templated tin(IV) phosphate has been isolated and its structure solved from powder X-ray diffraction data; it exhibits a one-dimensional inorganic network built up from chains of trimers of tin(IV) octahedra on which phosphate tetrahedral groups are grafted interacting with water molecules and organic moieties.     

Crown ether-appended Fe (III) porphyrin: Synthesis, characterization and catalytic oxidation of cyclohexene with molecular oxygen

A new crown ether appended Fe(Ⅲ) porphyrin complex was prepared by sulfuryl chloride appended benzo-15-crown-5 to the meso position of meso-5,10,15,20-tetra(4-hydrophenyl)porphyrin,and it was applied to catalytic oxidation of cyclohexene with molecular oxygen without reductant,showing a remarkable catalytic activity(conversion is up to 94%) and selectivity for 2-cyclohexen-1-ol(73%).     

Electron Transfer Studies of TIN(IV)/TIN(II) in Acid Media

Abstract

Cyclic voltammaetry of mixed tin(II)/tin(IV) solutions was investigated in 6M HCl on gold and mercury electrodes. It was found that the reduction of tin(II) to tin(iv) proceeded irreversibly while tin(II) to tin(IV) was reversible. Two forms of tin(IV) are postulated. The peak potential for the reduction of tin(IV) was a function of both tin(II) and tin(IV) while that for the oxidation of tin(II) was a function only of tin(II) concentration Potentials for all oxidations and reductions were a function of potential scan rate.     

Imparting Multifunctionality by Utilizing Biporosity in a Zirconium-Based Metal–Organic Framework

In this work, we have synthesized nanocomposites made up of a metal–organic framework (MOF) and conducting polymers by polymerization of specialty monomers such as pyrrole (Py) and 3,4-ethylenedioxythiophene (EDOT) in the voids of a stable and biporous Zr-based MOF ( UiO-66 ). FTIR and Raman data confirmed the presence of polypyrrole ( PPy ) and poly3,4-ethylenedioxythiophene ( PEDOT ) in UiO-66-PPy and UiO-66-PEDOT nanocomposites, respectively, and PXRD data revealed successful retention of the structure of the MOF. HRTEM images showed successful incorporation of polymer fibers inside the voids of the framework. Owing to the intrinsic biporosity of UiO-66 , polymer chains were observed to selectively occupy only one of the voids. This resulted in a remarkable enhancement (million-fold) of the electrical conductivity while the nanocomposites retain 60–70 % of the porosity of the original MOF. These semiconducting yet significantly porous MOF nanocomposite systems exhibited ultralow thermal conductivity. Enhanced electrical conductivity with lowered thermal conductivity could qualify such MOF nanocomposites for thermoelectric applications.     

Imparting Multifunctionality by Utilizing Biporosity in a Zirconium‐Based Metal–Organic Framework

In this work, we have synthesized nanocomposites made up of a metal–organic framework (MOF) and conducting polymers by polymerization of specialty monomers such as pyrrole (Py) and 3,4‐ethylenedioxythiophene (EDOT) in the voids of a stable and biporous Zr‐based MOF ( UiO‐66 ). FTIR and Raman data confirmed the presence of polypyrrole ( PPy ) and poly3,4‐ethylenedioxythiophene ( PEDOT ) in UiO‐66‐PPy and UiO‐66‐PEDOT nanocomposites, respectively, and PXRD data revealed successful retention of the structure of the MOF. HRTEM images showed successful incorporation of polymer fibers inside the voids of the framework. Owing to the intrinsic biporosity of UiO‐66 , polymer chains were observed to selectively occupy only one of the voids. This resulted in a remarkable enhancement (million‐fold) of the electrical conductivity while the nanocomposites retain 60–70 % of the porosity of the original MOF. These semiconducting yet significantly porous MOF nanocomposite systems exhibited ultralow thermal conductivity. Enhanced electrical conductivity with lowered thermal conductivity could qualify such MOF nanocomposites for thermoelectric applications.     

Carbonyl allylations by allylic chlorides utilizing a reduction of tin(IV) iodide to triiodostannate(II) species with iodide sources

Carbonyl allylations by allylic chlorides either with tin(IV) iodide and tetrabutylammonium iodide (TBAI) in dichloromethane or with tin(IV) iodide and sodium iodide in 1,3-dimethylimidazolidin-2-one at room temperature produced the corresponding homoallylic alcohols. The carbonyl allylations probably proceeded via the reduction of tin(IV) iodide to triiodostannate(II) species with iodide sources such as TBAI and NaI, which led to the construction of a tin(IV)-catalytic cycle based on regeneration of tin(IV) iodide via the transmetalation of homoallyloxytriiodotin to homoallyloxytrimethylsilane with iodotrimethylsilane.     

In Process Citation

The sample (up to 5 mg) is destroyed by using a wet process in a glass flask of the Kjeldahl type. Aluminium cobalt, tin and iron are determined spectrophotometrically. The following reactions are used: complexation of aluminium by Alizarin Red S and calcium cobalt(II) by tiron tin(IV) by phenylfluorone, iron(III) by tiron.     

Effect of citric acid and hydrochloric acid on the polarographic behaviour of tin: Application to the determination of tin(II) in presence of tin(IV) in the activating solutions of the electroless plating of polymers

A new method for the determination of tin(II) in presence of tin(IV) is described. The method is based on differential pulse polarography on the hanging mercury drop electrode (HMDE). The effect of citric acid and hydrochloric acid concentrations on the polarographic peaks of tin(II) and tin(IV) has been studied. In 1 M HCl, the total quantity of tin can be determined, as under these conditions, in the absence of complexing agents, eventual variations in the oxidation states, in any concentration ratio, do not affect the peak height and the peak potential. In 0.2 M HCl and 0.2 M citric acid, tin(II) can be determined selectively in presence of tin(IV), as under these conditions, tin(IV) does not present polarographic response, while a well-defined peak is observed for tin(II). The method is applied to determine tin(II) and total tin in the activating solutions of the electroless plating of polymers.     

Darstellung und NMR-spektroskopische Charakterisierung von konfigurationsstabilen Diorganozinn(IV)-Komplexen RPhSnL mit Zinn als chiralem Zentrum

Synthesis and Characterization of Configurationally Stable Diorganotin(IV) Complexes with Tin as a Chiral Centre Contrary to the high optical stability of tetraorganotin compounds most heteroleptic organic tin compounds are configurationally instable. We report the synthesis and the characterization of some new enantiomeric and diastereomeric diorganotin(IV) complexes of stable configuration with tin as a chiral centre. The stabilization of the chiral tin atom was realized by complexation with tridentate diacidic esterhydrazone ligands H₂L, which prevent an interconversion at the stereogenic centre. Multinuclear NMR-studies in solution demonstrate, that the configuration of the chiral tin center is configurationally stable up to 160°C. The molecular structure of the complexes Neophyl-phenyl-tin-2[(2-methyl-mercaptothiocarbonyl)-hydrazono]propionate II b and (2-Methyl-butyl-1-yl)-phenyl-tin-[S-methyl-β-N-(2-salicylmethylidene)thiocarbazat] III g have been determined by single crystal X-ray diffraction analysis.     

Self‐assembly of metal–organic framework thin films containing metalloporphyrin and their photocatalytic activity under visible light

With [5,10,15,20‐tetra(4‐carboxyphenyl)porphyrin]Mn(III) and sterically controlled 2,2¢‐dimethyl‐4,4¢‐pyridine as the main raw materials, metal–organic framework thin films containing metalloporphyrin (MnPor‐MOF) with catalytically active sites were built up on functionalized quartz glass surfaces using a layer‐by‐layer self‐assembly method. Retaining active catalytic sites and having a porous reticular structure, the MnPor‐MOF films possessed remarkable photocatalytic activity for oxidative degradation of methylene blue in the presence of hydrogen peroxide under visible‐light irradiation. Most meaningfully, the MnPor‐MOF films were highly stable and simply and conveniently reusable, and are thus a potentially new organic material for photocatalytic wastewater treatment. Copyright © 2015 John Wiley & Sons, Ltd.     

X-Ray crystal structure of [HSm{V(IV)O(TPPS)}]n and encapsulation of nitrogen molecules in 1-D channels

The crystal structure of an N(2)-encapusulated MOF, which is stable under open-air conditions at ambient temperature, was determined by single-crystal X-ray diffraction at 123 K. The crystal MOF of [HSm{V(IV)O(TPPS)}](n) designed to have 1-D channels periodically constricted by porphyrins planes adsorbed N(2) at 77 K. The adsorbed N(2) molecules remained in the 1-D channels even after warming to ambient temperature. The single-crystal structure of [HSm{V(IV)O(TPPS)}](n)?N(2) determined by X-ray diffraction indicated that N(2) molecules trapped in the constricted parts block other N(2) molecules in 1-D channels from escaping from the MOF. Such a unique encapsulation mode provides a promising approach toward designing novel MOFs with high gas storage capacity at ambient temperature.     

The complexometry of tin(IV)

Tin(IV) very readily hydrolyses in solution, and forms hydrous tin oxide SnO(2)2.nH(2)O even in rather strongly acidic solution. In spite of a lack of reliable data on the hydrolysis of tin(IV) a consistent picture of the behaviour of tin(IV) in solution has been constructed. Some values for the formation of hydroxide and chloride complexes were deduced from electrochemical data. In agreement with more or less qualitative remarks by other investigators a value of log k(so) = -3 has been found for the solubility constant. For the stability constant of tin(IV)-EDTA, log K(SnY) = 34.5 was found experimentally. A survey is given of the pitfalls which exist in handling tin solutions. A back-titration procedure is presented that provides for the complexometric determination of tin(IV) at concentrations down to 3 ppm, with an error of 1% or better. Thorium is used as back-titrant with Semi-Xylenol Orange as indicator. The method has successfully been applied to the analysis of organotin compounds.     

Synthesis of both epimeric triacid ananlogs of kainic acid

A practical and cheap method for synthesis of C-4 carboxylic acid substituted kainic acid analogue 5 and its epimer 6 from trans-4-hydroxyproline is described. Using this method, more interesting intermediates and analogues could be obtained easily.     

Enhanced Sieving of C2-Hydrocarbon from Methane by Fluoro-Functionalization of In-MOF with Robust Stability

Developing efficient adsorbent materials is crucial for adsorption and separation to realize the purification of energy source and raw chemicals. Here, we report a novel and robust 3D In-based MOF built up with fluorine-functionalized ligands, QMOF-2F , with improved separation properties of C2-light hydrocarbons over methane at room temperature respect isoreticular non-fluorinated MOF. QMOF-2F shows a remarkable chemical stability in different solvents, including water, and pH (2–12). DFT calculations support the key role of fluorine-functionalization on the improved performance of QMOF-2F .     

Two‐Dimensional Metal–Organic Framework Nanosheets for Membrane‐Based Gas Separation

Metal–organic framework (MOF) nanosheets could serve as ideal building blocks of molecular sieve membranes owing to their structural diversity and minimized mass‐transfer barrier. To date, discovery of appropriate MOF nanosheets and facile fabrication of high performance MOF nanosheet‐based membranes remain as great challenges. A modified soft‐physical exfoliation method was used to disintegrate a lamellar amphiprotic MOF into nanosheets with a high aspect ratio. Consequently sub‐10 nm‐thick ultrathin membranes were successfully prepared, and these demonstrated a remarkable H₂/CO₂ separation performance, with a separation factor of up to 166 and H₂ permeance of up to 8×10⁻⁷ mol m⁻² s⁻¹ Pa⁻¹ at elevated testing temperatures owing to a well‐defined size‐exclusion effect. This nanosheet‐based membrane holds great promise as the next generation of ultrapermeable gas separation membrane.