【作者】 施锋；

【导师】 彭孝军； 孙立成；

【作者基本信息】 大连理工大学 ， 应用化学， 2004， 博士

【摘要】 将多酚多齿配体同光敏体[Ru（bpy）₃]²⁺共价连接得到了化合物21和22。在这两个化合物中,引入了更多的酚羟基和供电取代基（叔丁基、吗啉环）。引入的酚氧负离子对吡啶上的中性氮原子的替代可使中心金属形成更高的氧化价态—M₂（Ⅲ,Ⅲ）,同时由于O^-更强的配位能力也有效地防止了M的解离。同时供电性基团——叔丁基和吗啉环的引入还提高了配合物的溶解度并改善了其电化学性质。化合物22上两个突出的吗啉环预期可通过“N…H—O—H…N”的氢键与水分子作用,这将促进水的氧化过程进行。重要的是在这两个化合物中还保持了原模型中类似于自然界酪氨酸与His190之间形成氢键这一构型上的优势。 对化合物21及22闪光光解实验中,观测到了从模拟酪氨酸的酚羟基部分到光激发产生的Ru（Ⅲ）的分子内电子转移。同时它们的电子转移速度较化合物20快了两个数量级,推测这是由于酚羟基与吡啶环之间形成的氢键作用引起的。 21,22中的(Ru（bpy）₃]²⁺上引入四个酯基合成了化合物29及30,酯基的引入不仅提高了光敏体中金属Ru的氧化电位,使其更易将配位的双核金属氧化至较高价态;又使这两个化合物具备了附着在半导体TiO₂的条件。通过闪光光解测试,470 nm处Ru（Ⅱ）吸收的恢复伴随着410 nm处一个新的特定吸收的出现。这个特征吸收归属于酚羟基自由基的信号,这与酪氨酸的自由基相似,获得了较长电荷分离态的可能。 将多酚配体21及22分别配位上Mn、Ru、Fe等不同金属构建了三核M₂-[Ru^Ⅱ（bpy）₃]的配合物模拟PSⅡ的给体部分。通过循环伏安法,荧光分析法,纳秒激光闪光光解技术对这些配合物的氧化—还原特性,吸收特性,激发态寿命,量子产率,时间分辨吸收,瞬态吸收及分子内电子转移等性能进行研究。纳秒闪光光解研究发现配合的双核金属可向光氧化产生的Ru（Ⅲ）传递电子,发生光诱导分子内电子转移。电化学研究表明在此类配合物中Ru（Ⅲ/Ⅱ）电位高于M₂（Ⅲ,Ⅲ）/M₂（Ⅲ,Ⅴ）甚至M₂（Ⅲ,Ⅴ）/M₂（Ⅳ,Ⅳ）的电位,使光转化过程产生高价金属氧化中心成为可能。更多还原

【Abstract】 The phenol ligands with -NH2 group were linked with the Ru(Ⅱ) tris-bipyridine to construct 21 and 22. And the two compounds are coordinated manganese, ruthenium and ferric respectively, to construct other six complexes. Their redox potentials, luminescence intensities, lifetimes, quantum yields, time-resolved absorbance, transient absorbance, kinetics decay and electron transfer are studied by use of cyclic vottammetry, photoluminescence analysis and nanosecond laser flash photolysis.Although the exact mechanism of photosynthetic water oxidation is not solved, it is clear that the Mn ions in the higher oxidation states of the S-cycle are at the MnⅢ state or higher. In order to get a Mn (Ⅲ,Ⅲ) dimmer complex with high oxidation states of manganese to increase the possibility of storing more oxidizing equivalents necessary to oxidize water evolving oxygen, some pyridyl groups in Hbpmp are replaced by anionic phenolate groups as compounds 21, 22. Simultaneously, the stronger coordinate band O-Mn than N-Mn prevents dissociation of the Mn dimmer in aqueous solution (which is a problem with dpa-based systems). Introduction of tert-butyl groups to the ligand not only improves the solubility of complex, but also mcreases their electron donating effect that may result in lower redox potentials for the manganese redox complex. The two"out-standing" arms of morpholine on tert-Butyl-phenol was expected to provide the function of anchoring water via a chain "N…H-O-H…N" by the hydrogen bound function between two nitrogen atoms in morpholine and two hydrogen atoms in water.The maximum of the MLCT at two compounds 21, 22 are red shifted with the respect to that of Ru(bpy)3. These spectra variances are due to the different ligands in the compounds. Through the laser flash photolysis, the results mean the regeneration of Ru(Ⅱ) is due to the intramolecular electron transfer from the substituted phenol(s) to the photooxidized Ru(Ⅲ). And the electron transfer rate is almost two orders of magnitude faster than that of the compound 20. The hydrogen-banding between the pyridine and the phenol group could be responsible for the fester electron transfer, analogous to the proposed interaction between tyrosine and His190 in PSII. In addition, we present two new compounds 29, 30, in which the ligands are linked to ruthenium tris-bipyridine with four ester groups. The ester groups on the bipyridyl ligands provide a possibility to attach these compounds to TiO2. When the hydrolyzed compound 29 was attached to TiO2, fast intermolecular electron transfer observedhere can efficiently compete with charge recombination between oxidized sensitizer and reduced semiconductor TiO2, which provide a possibility to attain a long lifetime of charge-separated state.We coordinate Mn, Ru and Fe into the ligand 21, 22 to construct the metal complexes M2-[RuⅡ(bpy)3]. According to the fitting of 470 nm trace in complex 32, RuⅡ recovery occurred with kET> 8.2 ×107 s-1. We attribute this to intramolecular electron transfer from the Mn2(Ⅲ,Ⅲ) moiety, most likely generating the Mn2(Ⅲ, Ⅳ)complex. And in complex 33, the transient absorption data indicate that, Ru(Ⅱ) can be photooxidized to Ru(Ⅲ) and then reduced by very fast intramolecular electron transfer from the coordinated dinuclear ruthenium moiety. The above results demonstrate that these complexes can be applied for photo-induced oxidized models research.更多还原