微粒體甲烷單氧化酵素之結構與功能性之模型三核銅金屬簇化物之研究(IV)
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2012
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在先前的研究中，我們已經發展出配位基7-Dipy能與三當量的[CuI(CH3CN)4](BF4)配位形成三核銅金屬簇離子化合物[CuICuICuI(7-Dipy)](BF4) (1)。且室溫、常壓下，此三核銅簇化物[CuICuICuI(7-Dipy)](BF4) (1) 加入雙氧水可以有效催化氧化環己烷 (C6H12) 的碳氫鍵 (C－H鍵能為99.3 kcal/mol) 生成環己醇 (C6H12O) 和環己酮 (C6H10O)。而三核銅簇化物[CuICuICuI(7-Dipy)](BF4) (1) 通入氧氣或兩當量的雙氧水可得穩定的三核銅金屬含氧簇離子化合物[CuIICuII(µ-O)CuII(7-Dipy)](BF4)2 (2)。
在我的研究中，藉由另外的實驗方法得到的400 MHz 1H-NMR 和ESI-MS光譜，再次證實7-Dipy加入三當量的[CuI(CH3CN)4](BF4)確實會生成三核銅簇化物[CuICuICuI(7-Dipy)](BF4) (1)。此外，在相同的催化條件下，我們發現單銅金屬離子化合物[CuI(CH3CN)4](BF4) (7)、[CuI(bispicolylamine)](BF4) (8)相較三核銅金屬簇離子化合物[CuICuICuI(7-Dipy)](BF4) (1) 對於環己烷的催化反應活性並不高。而對催化反應的時間追蹤做研究，發現三核銅簇化物[CuICuICuI(7-Dipy)](BF4) (1) 在反應45分鐘時H2O2會被耗盡。
為了更進一步了解三核銅簇化物在進行催化反應時，是屬於自由基反應還是經由單氧直接嵌入的一步反應機構，因此我們設計一系列的實驗，利用對自由基相當靈敏的DMPO去檢測三核銅簇化物[CuICuICuI(7-Dipy)](BF4) (1) 在加入雙氧水進行催化反應時，是否有自由基反應的參與。EPR光譜圖顯示，可以排除三核銅簇化物[CuICuICuI(7-Dipy)](BF4) (1) 加入雙氧水進行催化反應時是屬於自由基反應機構。
關鍵字:微粒體甲烷單氧化酵素、三核銅金屬簇化物、催化
In previous study, a ligand 7-Dipy has been synthesized, and it can coordinate with tree equivalents of [CuI(CH3CN)4](BF4) to form a trinuclear copper complex [CuICuICuI(7-Dipy)](BF4) (1). This trinuclear copper complex [CuICuICuI(7-Dipy)](BF4) (1) catalyst is able to oxidize the C－H bonds of cyclohexane (C－H BDE = 99.3 kcal/mol) to cyclohexanol and cyclohexanone with high turnover frequencies in the presence of H2O2 in acetonitrile under ambient conditions. The oxygenation of [CuICuICuI(7-Dipy)](BF4) (1) either by dioxygen or two equivalents of H2O2 will obtain a stable [CuIICuII(µ-O)CuII(7-Dipy)](BF4)2 (2). In my study, 400 MHz 1H-NMR and ESI-MS spectra demonstrate that the 7-Dipy add tree equivalents of [CuI(CH3CN)4](BF4) will obtain [CuICuICuI(7-Dipy)](BF4) (1) complex. In the same catalytic conditions, we found that mononuclear copper complexes [CuI(CH3CN)4](BF4) (7) and [CuI(bispicolylamine)](BF4) (8) compared to trinuclear copper complex [CuICuICuI(7-Dipy)](BF4) (1) a significantly lower level of cyclohexane is oxidized. A time-course study indicates that the H2O2 used to turn over the trinuclear copper complex [CuICuICuI(7-Dipy)](BF4) (1) catalyst for substrate oxidation is already exhausted within 45 min. To further understand the trinuclear copper complex [CuICuICuI(7-Dipy)](BF4) (1) carrying out catalytic reaction are free radical mechanism or direct oxene insertion mechanism, therefore, we designed a series of experiments using very sensitive to free radicals DMPO, to detect the trinuclear copper complex [CuICuICuI(7-Dipy)](BF4) (1) by adding H2O2 for the catalytic reaction whether involvement free radical mechanism. EPR spectra demonstrate that trinuclear copper complex [CuICuICuI(7-Dipy)](BF4) (1) catalytic reaction can rule out the involvement of free radical mechanism. Key Word:Particulate Methane Monooxygenase、Trinuclear Copper Clusters、Catalysis
In previous study, a ligand 7-Dipy has been synthesized, and it can coordinate with tree equivalents of [CuI(CH3CN)4](BF4) to form a trinuclear copper complex [CuICuICuI(7-Dipy)](BF4) (1). This trinuclear copper complex [CuICuICuI(7-Dipy)](BF4) (1) catalyst is able to oxidize the C－H bonds of cyclohexane (C－H BDE = 99.3 kcal/mol) to cyclohexanol and cyclohexanone with high turnover frequencies in the presence of H2O2 in acetonitrile under ambient conditions. The oxygenation of [CuICuICuI(7-Dipy)](BF4) (1) either by dioxygen or two equivalents of H2O2 will obtain a stable [CuIICuII(µ-O)CuII(7-Dipy)](BF4)2 (2). In my study, 400 MHz 1H-NMR and ESI-MS spectra demonstrate that the 7-Dipy add tree equivalents of [CuI(CH3CN)4](BF4) will obtain [CuICuICuI(7-Dipy)](BF4) (1) complex. In the same catalytic conditions, we found that mononuclear copper complexes [CuI(CH3CN)4](BF4) (7) and [CuI(bispicolylamine)](BF4) (8) compared to trinuclear copper complex [CuICuICuI(7-Dipy)](BF4) (1) a significantly lower level of cyclohexane is oxidized. A time-course study indicates that the H2O2 used to turn over the trinuclear copper complex [CuICuICuI(7-Dipy)](BF4) (1) catalyst for substrate oxidation is already exhausted within 45 min. To further understand the trinuclear copper complex [CuICuICuI(7-Dipy)](BF4) (1) carrying out catalytic reaction are free radical mechanism or direct oxene insertion mechanism, therefore, we designed a series of experiments using very sensitive to free radicals DMPO, to detect the trinuclear copper complex [CuICuICuI(7-Dipy)](BF4) (1) by adding H2O2 for the catalytic reaction whether involvement free radical mechanism. EPR spectra demonstrate that trinuclear copper complex [CuICuICuI(7-Dipy)](BF4) (1) catalytic reaction can rule out the involvement of free radical mechanism. Key Word:Particulate Methane Monooxygenase、Trinuclear Copper Clusters、Catalysis
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微粒體甲烷單氧化酵素, 三核銅金屬簇化物, 催化, Particulate Methane Monooxygenase, Trinuclear Copper Clusters, catalysis