نتایج جستجو برای: α keggin
تعداد نتایج: 165395 فیلتر نتایج به سال:
Transition-metal substituted Keggin-type polyoxometalates (POMs) are of great interest for applications in biomedicine, material science and catalysis. The synthesis transition metal-substituted polytungstates via the formation a lacunary...
A Keggin-type polyoxometalate (Cs(1.5)H(1.5)PW(12)O(40))-supported Pd catalyst is efficient for the direct synthesis of H(2)O(2) from H(2) and O(2) in the absence of any acid or halide additives under atmospheric pressure.
A large manganese-doped polyoxotitanate nanocluster Ti28MnO38(OEt)40H2, has been synthesized solvothermally. Its structure is arranged around the four-coordinate Mn(2+) dopant atom in a Keggin-type structure. A significant reduction of the band gap relative to that of undoped polyoxotitanate clusters is observed.
The templating effect of the Keggin polyanion derived from phosphotungstic acid (PTA) during the synthesis of NH(2)-MIL-101(Al) has been investigated by means of in situ SAXS/WAXS. Kinetic analysis and structural observations demonstrate that PTA acts as a nucleation site and that it stabilizes the precursor phase NH(2)-MOF-235(Al). Surprisingly kinetics of formation are little changed.
Ru nanoparticles loaded on a Keggin-type polyoxometalate (Cs(3)PW(12)O(40)), which did not possess strong intrinsic acidity, efficiently catalysed the conversions of cellobiose and cellulose into sorbitol in water medium in H(2) at ≤433 K. The Brønsted acid sites generated in situ from H(2) have been demonstrated to play a key role in the formation of sorbitol.
An efficient and improved procedure for the synthesis of 1,4-diazepine and 1,5-benzodiazepine derivatives via the reaction of ketimine intermediates with aldehydes in the presence of Keggin-type heteropolyacids (HPAs) was developed. High yields and short reaction times were obtained for both electron-releasing and electron-withdrawing substituted 1,4-diazepine and 1,5-benzodiazepines derivatives.
H+ modulated charge-transfer in photoexcited covalently linked W and Mo Keggin-bodipy conjugates is demonstrated using transient absorption spectroscopy photoluminescence. Adding acid switches on (W) or accelerates (Mo) charge separation.
Using carbon monoxide as a probe molecule for the oxidation state of Cu ions, we demonstrated that anchored polynuclear charge-transfer complexes consisting of Ce(III) ions and Cu(II)-substituted Keggin-type polyoxotungstates function as efficient visible-light-driven multielectron-transfer catalysts.
A novel (3,4)-connected 3D self-penetrating metal-organic framework with a nanometre-scale cavity constructed from metallacalix[4]arene building blocks and Keggin-type polyanions has been obtained by using a 1,3-bis(1-methyl-5-mercapto-1,2,3,4-tetrazole)propane ligand.
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