【作者】 高岩；

【导师】 孙立成； 刘建辉；

【作者基本信息】 大连理工大学 ， 精细化工， 2007， 博士

【摘要】 天然光合作用将太阳能转化为化学能，这是地球上所有生物赖以生存的过程。在光合作用中，维持能量所需的电子来源于光驱动的水氧化过程。在光系统二的活性中心，叶绿素(P₆₈₀)吸收太阳光，将电子传递给电子受体、醌A和醌B，同时光氧化的P₆₈₀⁺从释氧中心（OEC）中得回电子（通过Tyr_z氧化Mn4Ca簇），经过四次光诱导电子转移，两分子水最终被氧化生成一分子氧气。而本论文构建OEC模型的目的正是在于研究电化学或光驱动的催化水氧化。本论文分别设计并构建了下列三类模型体系：1、氧杂蒽Corrole配体5，6及高价的金属络合物Mn^Ⅳ（7，9）和Cu^Ⅲ（8，10）模拟释氧中心（OEC）；2、Boc保护的酪氨酸Corrole化合物13，14及高价金属金属络合物Cu^Ⅲ（15，17）和Mn（16，18，18’）模拟OEC中的Tyr-Z和Mn4Ca簇；3、三联吡啶钌通过酰胺键连接的铜Corrole络合物22模拟P₆₈₀和OEC。本论文共合成了20种新化合物，并利用核磁、质谱、紫外可见光谱、元素分析、电化学等多种手段对大部分化合物的结构和性质进行了研究。我们根据文献的方法从硝基化合物2出发，经过还原和酰化反应得到单臂5和双臂6氧杂蒽Corrole配体化合物，分别与铜锰络合得到金属络合物7～10。通过质谱、紫外可见光谱、电化学等方面的研究，确定了锰络合物7和9金属中心的价态为Mn（Ⅳ）。利用循环伏安法研究了金属络合物7～10的电化学性质，发现金属锰化合物能够在较低的电压下被氧化成高价金属络合物，并证明Corrole配体化合物能够很好地稳定高价金属。在电化学条件下，锰化合物7，9在较低电压下（大约0.80 V vs Ag／Ag+）表现出催化水氧化的性能，产生的氧气利用电化学和氧电极检测，同时确定双臂金属锰络合物9的催化效率明显的高于单臂金属锰络合物7。而金属铜络合物8、10在催化水氧化过程中没有表现出任何活性。其次，为了更好地解释释氧中心OEC与Tyr之间的相互作用，本文合成了Tyr-Corrole化合物15～18、18’。通过同样的方法确定了锰化合物16、18的价态为Mn（Ⅳ），而化合物18’的价态为Mn（Ⅲ）。通过金属络合物15～18、18’的电化学曲线，发现Tyr基团上苯酚的氧化电位明显高于Corrole环和Mn^Ⅲ／Mn^Ⅳ的氧化电位，说明具有氧化性的Tyr自由基，可以通过电子转移实现对金属Corrole环的氧化。同时，我们得到化合物17的晶体结构，确定了化合物中各个基团的结构和相对位置，为更好的模拟释氧活性中心提供了很好的依据。应用金属Tyr-Corrole络合物在电化学、化学和光化学条件下研究催化水氧化，没有发现放氧产生。我们最终目的是实现光驱动水氧化，所以本文采用两种不同方法得到了Ru（bpy）₃Cu-Corrole化合物22。通过金属Ru-Cu络合物22的电化学研究发现Ru^Ⅱ／Ru^Ⅲ的氧化电位明显高于Corrole环；并且通过对比化合物[Ru（bpy）₃]²⁺的发射光谱发现化合物22发射光谱发生了明显的淬灭，这说明可以通过光照实现[Ru（bpy）₃]²⁺与铜Corrole两部分之间的分子内电子或能量转移。本文通过引入高价Mn（Ⅳ）-Corrole化合物，建立了一套较为完整的在结构或功能上模拟包括P₆₈₀、Tyr_z、OEC的模型体系。锰化合物7和9实现了碱性条件下的电化学水氧化放氧，而铜化合物在此条件并没有表现出催化水氧化性能。更多还原

【Abstract】 Solar energy is converted into chemical energy by photosynthesis in nature, a processwhich keeps all living forms to survive on the earth. The electrons used to sustain the energycome from the light driven water oxidation. This happens in a so called reaction center inPhotosystemⅡ（PSⅡ）, where a tetrameric chlorophylls （P680） absorb the solar light andinitiate photoinduced electron transfer reaction to the acceptors, quinone A and B. Thephoto-oxidized P680 retrieves the electron from a Mn4Ca cluster via a tyrosine（Tyr-Z）, thelatter components are also called oxygen evolving center （OEC）. After 4 photo-processes, twomolecular water are oxidized to a molecular oxygen. In this thesis, efforts to make syntheticmodels of OEC aiming for catalytic water oxidation driven either by electrochemistry or bylight have been made. Three different model systems have been designed and synthesized: 1.two corrole xanthene ligands 5, 6 and four corresponding high valence Mn^Ⅳ（7, 9） and Cu^Ⅲ（8, 10） complexes for the mimic of oxygen evolution center （OEC）; 2. Boc-protectedtyrosine-attached corrole compounds 13, 14 and corresponding high valence copper （15, 17）and manganese （16, 18, 18’） complexes for the mimic of Tyr-Z and Mn4Ca in OEC; 3. Acopper-corrole complex linked to a ruthenium（Ⅱ） tris（bipyridine） complex 22 with an amidebond to mimic the P₆₈₀ and OEC. Totally 20 new complexes are synthesized, andcharacterized by ¹H NMR, MS, UV-vis, mass-spectrometry, elemental analysis, et al.The synthesis starts from a nitro-corrole compound 2 which was prepared according to theliterature method. After reduction of the nitro group in 2, the obtained amine compound isused to synthesize the desired single armed corrole compound 5 （HCX） and the double armedcorrole compound 6 （BCX）. A subsequent coordination of metal ions to 5 and 6 givescorresponding complexes 7, 8, 9 and 10. Through the measurements of MS, UV-vis andelectrochemistry, the valence state for the central metal ion of manganese complexes 7 and 9is confirmed to be Mn（Ⅳ）. By studying the cyclic voltammetry （CV） of metal complexes7～10, it was found that the manganese complexes can be relatively easily oxidized to highervalence and the corrole ligands are stable enough to steady high valent metal ions. Bothmanganese complexes 7 and 9 have shown catalytic water oxidation to evolve molecularoxygen at low potential （about 0.80 V vs Ag/Ag+） by electrochemical method and thegenerated O₂ was further confirmed by oxygen electrode detection. The complex 9 has highercatalytic activity than complex 7 on oxygen evolution. We also studied the catalytic functionsof copper corrole complexes, but no molecular oxygen was detectedin similar experimentalcondition. In order to mimic the function of Tyr in OEC, tyrosine-attached complexes 15～18, 18’ werealso synthesized. In the same manner, we can conform that the valence of Mn ion in complex16, 18 is Mn（IV） and 18’ is Mn（Ⅲ）. We studied the CV of metal Tyr-corrole complexes, andfound the oxidation potential of Tyr units was higher than the metal corrolering. The resultssuggested that the Tyr radical can oxidize metal corrole ring through electron transfer.Furthermore, we obtained a crystal structure of 17, which displays the relative position of Tyrto the high valent metal center and provided more useful information on mimicking the activecenter of OEC. We also studied the catalyzing water oxidation of metal complexes byelectrochemical, chemical, photochemical methods, but no oxygen was detected.Our final target is to obtain light-driven water oxidation. Therefore, we combined aphotosensitizer Ru（bpy）₃ with the Cu-corrole complex and we synthesized theRu（bpy）₃-Cu-corrole complex 22 in two different way. We found that the oxidation potentialof [Ru（bpy）₃]²⁺ unit was higher than the metal corrole unit. In addition, the emission ofRu（bpy）₃Cu-corrole complex 22 was found to have a substantial quenching when the MLCTof [Ru（bpy）₃]²⁺ was selectively photoexcited compared to the parent [Ru（bpy）₃]²⁺. Thisobservation suggested a quenching mechanism with possible intramolecular electron transferor energy transfer between the [Ru（bpy）₃]²⁺ moiety and the Cu corrole moiety.Insummary, we built up a relatively integrated model system to mimic either thestructure or the function of P₆₈₀, Tyr_z and OEC by using high valence Mn（Ⅳ）-corrolecomplexes. Catalytic water oxidation to evolve molecular oxygen in a basic condition byelectrochemical method has been achieved. However, no catalytic water oxidation has beenfound with Cu（Ⅲ）-corrole complexes in the similar experimental condition.更多还原