Integrated photocatalysts for hydrocarbon oxidation: polyoxotungstates/iron porphyrins systems in the reductive activation of molecular oxygen

详细信息    查看全文

• 作者：Molinari ; Alessandra ; Maldotti ; Andrea ; Amadelli ; Rossano ; Sgobino ; Anna ; Carassiti ; Vittorio
• 关键词：Polyoxotungstates ; Iron complexes ; Oxygen activation ; Porphyrin complexes ; Photocatalysis
• 刊名：Inorganica Chimica Acta
• 出版年：1998
• 出版时间：May 1, 1998
• 年：1998
• 卷：272
• 期：1-2
• 页码：197-203
• 全文大小：560 K

文摘

The photochemical and photocatalytic properties of (nBu₄N)₃PW₁₂O₄₀(PW₁₂O₄₀³⁻), (nBu₄N)₄W₁₀O₃₂ and (Et₄N)₄W₁₀O₃₂ (W₁₀O₃₂⁴⁻) were investigated in the presence of several Fe(III) meso-tetraarylporphyrins (Fe(III)Por). Laser flash photolysis experiments show that in the (nBu₄N)₃PW₁₂O₄₀/Fe(III) Por integrated systems the electron transfer from the photoreduced polyoxotungstate to the Fe(III)Por is the first step for the subsequent reductive activation of O₂ by the ferrous complex. In contrast, the direct reduction of O₂ by the photoreduced polyoxotungstate is the kinetically favored process in the (nBu₄N)₄W₁₀O₃₂/Fe(III)Por systems. A comparison between the results obtained using (nBu₄N)₄W₁₀O₃₂ and (Et₄N)₄W₁₀O₃₂ shows that the decrease in the steric hindrance of the counterion, surrounding the photochemically active polyoxoanion, increases the rate of electron transfer between W₁₀O₃₂⁵⁻ and Fe(III)Por, thus enabling the decatungstate to contribute to the activation of dioxygen through the reduction of the Fe(III)Por.