标题: | 仿生性双硫醇架桥-双核钌复合物及其衍生物模拟双硫铁产氢酶活化中心之研究 Biomimetic Study of the Active Site Center in [FeFe] Hydrogenase by Various Dithiolato-Bridged Dinuclear Ruthenium Complexes |
作者: | 詹欣芳 Chan, Hsin Fang 吴东昆 Wu, Tung-Kung 生物科技学系 |
关键字: | 氢能源;铁-铁产氢酶;氢簇分子;光催化产氢;双硫醇架桥之双核钌复合物;hydrogen energy source;[FeFe]-Hydrogenase;H-cluster;photocatalytic hydrogen generation;dithiolate diruthenium complexes |
公开日期: | 2010 |
摘要: | 氢能源是一种干净无污染并且可作为替代石化燃料的再生性能源。然而目前的氢气制备,主要是以蒸气重组 (steam reforming) 或电裂解水(water splitting)的方式来产氢,不仅效能不佳且成本昂贵。在自然界中,产氢酶与氢气的代谢息息相关,其主要是催化氢分子和氢质子之间的互相转换 (2H++2e- ⇆ H2)。在适合的反应环境条件下此酵素能快速地进行催化反应而产生氢气。近年来利用结晶学的技术,科学家已成功地解出Desulfovibrio desulfuricans 以及Clostridium pasteurianum中铁-铁产氢酶 ([FeFe]-Hydrogenase) 的X-ray晶体结构。而这类酵素活化中心的氢簇分子 (H-cluster) 就是使其具有高效能产生氢气的催化中心。因此我们的目标就在于模拟并合成出铁-铁产氢酶活化中心-氢簇分子(H-cluster)的化学结构-[(μ-DT)Fe2(CO)6] (DT: dithiolate),并以置换其中心金属、或在其双硫架桥上取代成不同的官能基以及修饰上不同的磷衍生物来探讨这些仿生酵素活化中心催化氢气产生的效率以及机制。我们合成了一系列双硫醇架桥之双核钌复合物 [Ru2(S2C3H6)(μ-X) (CO)6] (X=H, COOH, N-Boc) 去模拟氢簇分子 (H-cluster) 的结构,并藉由核磁共振光谱(NMR)、电喷洒质谱仪(ESI-MS)以及傅立叶转换红外线光谱 (FT-IR) 来分析及鉴定其结构。其后我们利用有机相和水相两种不同的反应系统来探讨这些有机双核钌金属复合物的产氢活性。在有机相系统中主要是以甲酸 (Formic acid, HCOOH) 来当作氢气来源,并外加三种具有不同的推拉电子特性之含磷化合物 (三苯基膦 (triphenylphosphine (P(Phe)3)), 三吡咯膦(tripyrrolephosphine (P(Pyr)3))及三吡咯啶膦(tripyrrolidinephosphine (P(Pyrldn)3)))来探讨其照光催化之产氢活性分析。另一方面,在水相光催化产氢系统中,我们是以抗坏血酸 (ascorbic acid) 当作电子提供者并辅以一个钌金属复合物光敏化剂 (Ru(bpy)32+),使得仿生有机双核钌金属复合物在照光条件下可以催化裂解水,并测得其在水相系统下之光催化产氢效率。在产氢活性的比较上,有机相反应的效率较水相来的好;而在有机相当中,又以三吡咯啶膦(P(Pyrldn)3)的添加更能够去增加其活性。在未来的应用上,我们希望透过此仿生性双核钌复合物的建构,对于铁-铁产氢酶 ([FeFe]-Hydrogenase) 其活化氢簇分子中心的催化产氢机制有更进一步的探讨,并使其能应用于未来氢能源工业上。 Hydrogen is regarded as a clean fuel and a promising alternative energy to fossil fuels, because current hydrogen production via water splitting is still inefficient and expensive. In contrast, hydrogenases (H2ases), which are enzymes for hydrogen (H2) evolution, catalyze the reversible inter-conversion of proton and hydrogen (2H++2e- ⇆ H2) with convenient and high efficiency under mild conditions. The crystal structures of one kind of hydrogenases, the [FeFe] hydrogenases from Desulfovibrio desulfuricans and Clostridium pasteurianum, have been elucidated by X-ray crystallography. The organometallic H-cluster unit of its active site is involved in hydrogen production and provided a very high rate of hydrogen generation. Our aim is to mimic the structure of the H-cluster, [(μ-DT)Fe2(CO)6] (DT: dithiolate) in [FeFe] hydrogenases, with the substitution of different metal center, replacement of bridging dithiolate ligands and the modification of various phosphine ligands to study their catalytic activity for hydrogen production. In this study, we first synthesize a series of ruthenium (Ru)-substituted H-cluster mimics (dithiolate diruthenium complexes [Ru2(S2C3H6)(μ-X) (CO)5L] (X=H, COOH, N-Boc). All of the artificial ruthenium (Ru)-substituted H-cluster mimics were characterized by IR, NMR and MS spectra. Further, the efficiency of photo-induced hydrogen production by using these compounds as catalysts were investigated in different phase systems. One is the organic phase which utilizes formic acid as hydrogen donor. The hydrogen evolution activity of synthesized ruthenium (Ru)-substituted H-cluster was investigated. Moreover, three kinds of phosphine ligands (triphenylphosphine (P(Phe)3), tripyrrolephosphine (P(Pyr)3) and tripyrrolidinephosphine (P(Pyrldn)3)) with different chemical-electronic properties were added inside to analyze their effect on hydrogen production efficiency. The other system is aqueous phase which needs a photosensitizer existence to process the light-driven water splitting reaction. In the presence of the (Ru)-substituted H-cluster functioning as a catalyst, Ru(bpy)32+ as a photosensitizer and ascorbic acid as a sacrificial electron donor, the reduction of water to H2 were studied. The results showed that the hydrogen evolution in organic phase is more efficient than that of aqueous phase. Moreover, in organic phase, P(Pyrldn)3 is the ligand with the best hydrogen generation efficiency. In the future, these artificial ruthenium-substituted H-cluster mimics will be one of promising catalysts in photoinduced hydrogen generation industry and the detailed mechanism of these artificial biomimetic hydrogenases will be further discussed. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#GT079828515 http://hdl.handle.net/11536/47724 |
显示于类别: | Thesis |