Glycol metalloporphyrin derivatives in solution or immobilized on LDH and silica: synthesis, characterization and catalytic features in oxidation reactions
Glycol metalloporphyrin derivatives in solution or immobilized on LDH and silica: synthesis, characterization and catalytic features in oxidation reactions
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DOI：
10.1039/c3cy00472d
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发表时间：
2014-01-01
影响因子：
5
通讯作者：
Nakagaki, Shirley
中科院分区：
文献类型：
--
作者：
Castro, Kelly A. D. F.;Simoes, Mario M. Q.;Nakagaki, Shirley
我们将[meso-四（五氟苯基）卟啉]与乙二醇反应，得到在meso-芳基的4位上被1 - 4个羟基烷氧基取代的卟啉。然后，我们将铁（III）或锰（III）插入到单取代和四取代的游离碱衍生物中，得到相应的金属卟啉配合物。接下来，我们将铁（III）和锰（III）卟啉固定在两种载体上：层状双氢氧化物（LDH）和二氧化硅（通过溶胶-凝胶过程合成）。我们使用粉末X射线衍射（PXRD），紫外-可见电子光谱和电子顺磁共振（EPR）表征所得固体，并研究了材料在均相和非均相介质中的催化活性。金属卟啉在（Z）-环辛烯氧化中提供了良好的催化转化率。对于环己烷的氧化，催化剂对醇的选择性而不是酮。在多相催化的情况下，固定化金属卟啉提供略低于产率相比，均相催化。然而，这些固体提供了一个主要优点：可重用性。实际上，在（Z）-环辛烯氧化的情况下，这些固体催化剂保持其活性至少三个循环。
We reacted [meso-tetrakis(pentafluorophenyl) porphyrin] with ethylene glycol to obtain porphyrins substituted with one to four hydroxyalkyloxy groups at position 4 of the meso-aryl groups. We then inserted iron(III) or manganese(III) into the mono-and tetra-substituted free-base derivatives, which afforded the corresponding metalloporphyrin complexes. Next, we immobilized the iron(III) and manganese(III) porphyrins on two supports: layered double hydroxide (LDH) and silica (synthesized by the sol-gel process). We characterized the resulting solids using powder X-ray diffraction (PXRD), UV-vis electronic spectroscopy, and electron paramagnetic resonance (EPR), and we investigated the catalytic activity of the materials in both homogeneous and heterogeneous media. The metalloporphyrins provided good catalytic conversions in (Z)-cyclooctene oxidation. As for cyclohexane oxidation, the catalysts were selective for the alcohol instead of the ketone. In the case of heterogeneous catalysis, the immobilized metalloporphyrins furnished slightly lower yields as compared with homogeneous catalysis. However, these solids presented a major advantage: reusability. Indeed, these solid catalysts retained their activity for at least three cycles in the case of (Z)-cyclooctene oxidation.