銅錯合物固定於功能性中孔洞二氧化矽奈米粒子應用在芳香族化合物氧化反應

Abstract

本論文將具有活性的銅模型錯合物固定於功能性二氧化矽奈米粒子的孔道中，以發產出兩種常溫下催化的仿生觸媒。這些異相觸媒能夠催化脂肪族及芳香族的碳氫鍵活化反應，並且可得到不錯的反應性及選擇性。實驗分為兩部分： (一) 我們合成了具有不同孔徑大小和不同矽鋁比的二氧化矽奈米球用以附載具有活性的三銅錯合物，用於苯環上碳氫鍵的活化反應。此種異相觸媒可在過氧化氫存在的條件下，將苯環轉化為酚及醌，並可藉由不同表面酸性程度影響催化反應的產物選擇性及活性，亦可藉由附載在二氧化矽奈米孔道中提升熱穩定性。此外，在勻相反應反應中，觸媒的分離、收集和重複使用較為困難，而使用二氧化矽奈米粒子的異相觸媒則可以藉由簡單的離心步驟而大大的降低此方面的難度。 (二) 第二部分則合成了一個三配位的銅錯合物用以模擬酵素的催化行為，在常溫下執行不同受質的催化反應。藉由附載在二氧化矽的奈米球孔道中，此種錯合物可以得到在常溫下仍穩定的活性中間體。此觸媒已知可將甲苯已相當高的轉化數催化為苯甲醇和苯甲醛，而本論文中則將測試其在不同受質上的催化反應結果，以進一步探討不同官能基及立體效應對此種觸媒催化活性的影響。

In this thesis, two kinds of biomimetic catalysts were developed by immobilizing active copper model complexes into the nanochannels of functionalized mesoporous silica nanoparticles (MSNs). These nanocomposites can efficiently catalyze oxidative reaction on C-H bond of aliphatic and aromatic compounds with high turnover number (TON) and selectivity at room temperature. The first kind of catalyst is based on a tricopper complex [(CuICuICuI)L]3+ (L = 3,3'-(1,4-diazepane-1,4-diyl)bis(1-(4-ethylhomopiperazin-1-yl) propan-2-ol) (7-Ethppz) and 3,3'-(1,4-diazepane-1,4-diyl)bis[1-(4-ethylpiperazine-1-yl) propan-2-ol] (7-Etppz)) which can perform oxidation of benzene to phenol and 1,4-benzoquinone in the presence of hydrogen peroxide. By immobilizing the complex in the functionalized MSNs, we observed both improved activity and stability of the complex due to structural stabilization in confinement spaces. Product distribution can, moreover, be altered via changing the property of MSNs. By introducing aluminum into the silica framework, adsorption amount of the complex can be increased because charge density on the surface of MSNs were significantly augmented. Another kind of copper complex is a tripodal tridentate copper complex, CuImph (Imph = bis(4-imidazolyl methyl)benzylamine), which can mediate the oxidation of aliphatic C-H bonds, e.g. toluene to benzyl alcohol and benzaldehyde. Stability and reactivity of the complex can also be promoted by immobilization in the nanospaces of MSNs. We have a go at using various hydrocarbons as starting materials, and we found that different functional groups and steric effect would influence the reactivity and selectivity of the catalyst.