釕聯吡啶錯合物進行光催化反應:碘離子氧化及苯醌還原反應

Abstract

本研究中釕錯合物經過照光激發後，與氧化淬熄劑 1,4-benzoquinone分別在水溶液、KNO3、pH 4 以及 pH 4 / KNO3 溶液中進行雙分子淬熄反應，得到對苯二酚。中間產物 Ru(bpy)33+再氧化I‾ 得到 I3‾。由於光化學產物 hydroquinone 和 triiodide 在水相中會互相反應而無法獲得最終產物，因此利用異相反應，將氧化淬熄劑 1,4-benzoquinone萃取在醋酸丁酯中，而釕錯合物和碘離子溶於水相中來進行反應。釕錯合物和氧化淬熄劑 1,4-benzoquinone 透過液面之間碰撞進行雙分子的淬熄反應，經由 Stern-Volmer equation 得知淬熄速率常數 kq 為7.43 x 108 M-1 s-1，淬熄後得到三價釕錯合物再與碘離子進行反應。最後得到的光化學產物 hydroquinone 和 triiodide，因hydroquinone 溶於有機相中且 triiodide 溶於水相中，能夠將兩種不同的產物分開，並利用電子吸收光譜鑑定其生成且計算出濃度。光化學反應是利用光能來驅動化學反應，而得到產物，並可以借以儲存部分光能。但也因為能量非常高，氧化和還原產物均為高活性之物質，所以一般光化學反應均針對氧化端或還原端之產物，單獨進行實驗設計。本研究首次將光化學反應用兩相的方式，將氧化產物及還原產物分別溶於不同溶劑中，以得到最大光轉換效率。In this research, the bimolecular quenching reaction of ruthenium complexes with the oxidative quencher 1,4-benzoquinone in aqueous, KNO3, pH 4, and pH 4 / KNO3 solutions after excitation to produce hydroquinone. The intermediate product, Ru(bpy)33+, then oxidizes I‾ to form I3‾.Due to the mutual reaction of the photochemical products hydroquinone and triiodide in the aqueous phase, which prevents obtaining the final products, a heterogeneous reaction was employed. The oxidative quencher 1,4-benzoquinone was extracted into butyl acetate, while the ruthenium complexes and iodide were dissolved in the aqueous for the reaction.The bimolecular quenching reaction between the ruthenium complexes and the oxidative quencher 1,4-benzoquinone occurred via collisions at the liquid interface. Using the Stern-Volmer equation, the quenching rate constant was determined to be 7.43 x 108 M-1s-1. After quenching, the trivalent ruthenium complex reacted with iodide.The final photochemical products were hydroquinone and triiodide, with hydroquinone dissolving in the organic phase and triiodide in the aqueous phase, allowing the separation of the two different products. The products were identified and their concentrations determined using electronic absorption spectroscopy.Photochemical reactions use solar energy to drive chemical reactions, resulting in products that can store part of solar energy. However, because of the high energy involved, both the oxidative and reductive products are highly reactive substances. Generally, photochemical reactions are designed to focus on either the oxidative or reductive products separately. This research is the first to use the heterogeneous reaction approach for photochemical reactions, dissolving the oxidative and reductive products in different solvents to achieve maximum solar conversion efficiency.