Novel Microporous Iron(III) Carboxylate Polymer Complexes Containing Metalloporphyrin: Synthesis and Heterogeneous Photo-oxidation Catalysis

The photo-oxidation catalysis of hydrocarbons with 1 atm dioxygen in a heterogeneous system is quite an interesting objective for both academic and industrial fields. The remarkable progress of the past decade in photocatalysis has been limited to ultraviolet light instead of the more useful visible-light region. The development of visible-light photocatalysts, therefore, has become one of the most important topics in photocatalysis research today. Here, we focused on the synthesis of novel microporous iron(III) carboxylate complexes having metalloporphyrins, Fe[MTCPP](M=Cu, Fe, Pd, Mn, Co; H_2TCPP=4,4\u27,4\u27\u27,4\u27\u27\u27-(21H, 23H-porphine-5, 10, 15, 20-tetrayl) tetrakis benzoic acid). The complexes were characterized by elemental analysis, TG/DTA, magnetic susceptibility, FT-IR, diffuse reflectance (DR) UV-vis, EPR, EXAFS, BET surface area, pore size distribution, and nitrogen occlusion measurements. In the DRUV-vis spectra, the iron complexes showed some adsorption bands in the visible-light region. Therefore, we demonstrated the catalytic activities of Fe[MTCPP] complexes for the photo-oxidation of hydrocarbons with 1 atm dioxygen under visible-light irradiation. Fe[PdTCPP] showed 37 turnover numbers after 3h for the photo-oxidation of cyclohexene, which was higher than those of the other iron(III) carboxylate complexes

Polyoxometalates and Microporous Transition Metal Carboxylates: Synthesis, Characterization, and Oxidation Catalysis

The oxidation of alkenes and alcohols with hydrogen peroxide (H_2O_2) and molecular oxygen, is quite an interesting objective for both academic and industrial fields. In this paper, we focused on polyoxometalates and microporous transition metal carboxylates as oxidation catalysts. For H_2O_2-based epoxidation reactions catalyzed by dimeric mono, di, and trititanium (IV)-substituted Keggin polyoxotungstates, trititanium (IV)-substituted Keggin polyoxotungstate was the most active because it exhibited the fastest formation rate of active hydroperoxotitanium (IV) intermediate. Furthermore, we investigated a novel method for the grafting reaction of transition metal-substituted polyoxometalates onto a silica surface. Keggin-type vanadium(V)-substituted polyoxomolybdate (PMoV) was electrostatically anchored to a modified silica surface having cationic ammonium moiety. The PMoV-grafted silica material exhibited activities higher than those of homogeneous PMoV reactions for the oxidation of various alcohols with 1 atm dioxygen in the presence of isobutyraldehyde (IBA). Microporous copper(II) carboxylates showed unique activities for the oxidation of alcohols with H_2O_2 in a heterogeneous system, in which a green-colored species, H_2[Cu_2^(OOCC_6H_10COO)_2(O_2)]・H_2O was one of the active oxidizing intermediates

Synthesis, X-ray Crystal Structure, and Photochromism of a Sandwich-Type Mono-Aluminum Complex Composed of Two Tri-Lacunary α-Dawson-Type Polyoxotungstates

The synthesis and molecular structure of a dimeric, mono-aluminum complex composed of two tri-lacunary α-Dawson polyoxometalates, [H14Al(B-α-P2W15O56)2]7− (1), is described herein. The tetra-n-butylammonium salt of 1, [(n-C4H9)4N]7[H14Al(B-α-P2W15O56)2] (TBA-1) was prepared by passing an aqueous solution of K6[B-α-H3P2W15O59{Al(OH2)}3]⋅14H2O through an ion-exchange resin column (H+-form), followed by addition of tetra-n-butylammonium bromide. Analytically pure and colorless crystals of TBA-1 were obtained via vapor diffusion from acetonitrile/methanol at ~25 °C. Single-crystal X-ray structure analysis revealed that a six-coordinate aluminum ion was sandwiched between two tri-lacunary α-Dawson-type units, resulting in an overall C2h symmetry. The characterization of TBA-1 was accomplished by elemental analyses, thermogravimetric/differential thermal analyses, Fourier-transform infrared spectroscopy, and solution 31P nuclear magnetic resonance spectroscopy. The photochromic properties of TBA-1 were also characterized in methanol under light irradiation (λ = 365 nm and ≥400 nm)

Heterogeneous esterification of fatty acids with methanol catalyzed by Lewis acidic organozirconium complexes with Keggin-type mono-aluminum-substituted polyoxotungstates

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Synthesis, X-ray Crystal Structure, and Photochromism of a Sandwich-Type Mono-Aluminum Complex Composed of Two Tri-Lacunary α-Dawson-Type Polyoxotungstates

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Syntheses, Molecular Structures, and Countercation-Induced Structural Transformation of Monomeric α-Keggin-Type Polyoxotungstate-Coordinated Mono- and Dipalladium(II) Complexes

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Two Tungstates Containing Platinum Nanoparticles Prepared by Air-Calcining Keggin-Type Polyoxotungstate-Coordinated Diplatinum(II) Complexes: Effect on Sintering-Resistance and Photocatalysis

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