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卟啉二聚体—苝二酰亚胺系列化合物的光致能量传递和光致电子转移研究
【作者】 徐薇；
【导师】 李希友；
【作者基本信息】 山东大学 ， 无机化学， 2008， 硕士
【摘要】 绿色植物光合作用反应中心是一个多步的电荷转移体系,这个体系是由一系列按照一定空间顺序排列的分子组成,具有很高的光致电荷转移和分离效率。在这种意义上说,自然界的植物光合作用反应中心是一种分子水平上的高效率的光伏器件。因此模拟生物光合作用中心的光致电子转移和能量转移对太阳能的光电转换和收集具有重要的理论和应用价值。分析给体-受体电子体系中光诱导电子转移和能量传递过程有助于改善对太阳能的捕获和储存。卟啉化合物是构成光合作用反应中心的主要染料分子-叶绿素的同系物,具有与叶绿素分子相似的光化学与光物理性质,是非常理想的人工光合作用研究中叶绿素分子的替代化合物,是非常理想的D-A体系中的供电子部分。苝二酰亚胺及其衍生物具有优异的化学和光热稳定性,在可见和紫外区都有很强的吸收,荧光发射强,量子产率高。虽然在普通有机溶剂中的溶解性不是很好,但可以通过引入取代基来提高其溶解性。因此近年来,苝二酰亚胺衍生物与卟啉衍生物相连的D-A体系受到越来越多的关注。但以卟啉二聚体与花二酰亚胺衍生物相连的D-A体系还很少见。本文首次开展了卟啉二聚体和苝二酰亚胺衍生物之间的光致能量传递和电子转移反应的研究,得到了一些有意义的结果。论文包括以下几个方面内容:1.综述了近几年来人工模拟光合作用研究进展以及各种卟啉-苝酰亚胺系列化合物的研究情况及其应用。2.合成并且表征了不同连接基(对苯二胺,乙二胺)相连的卟啉二聚体与苝二酰亚胺衍生物相连接的D-A体系化合物,作为对比我们还合成单卟啉与苝二酰亚胺衍生物相连的化合物。3.使用稳态电子吸收光谱,荧光光谱以及荧光寿命测量方法研究了化合物的光物理性质。稳态电子吸收光谱表明:在基态,卟啉二聚体中的两个卟啉分子之间有相互作用;而卟啉二聚体和苝二酰亚胺分子之间没有相互作用。荧光光谱表明了苝二酰亚胺向卟啉分子高效的光致能量传递和卟啉分子向苝二酰亚胺分子之间的光致电荷转移。这种光致能量传递不受连接基的影响,而卟啉分子向苝二酰亚胺的光致电子转移则明显的受给体受体之间的连接基以及溶剂极性的影响,且卟啉的二聚体结构在非极性溶剂中也加速了光致电子转移反应。
【Abstract】 The most important process in natural photosynthetic reaction center is the quick and efficient multiple-step electron and the energy transfer. This has attracted many researchers to look for ways to duplicate the reactions in simplified chemical systems. To mimic both the charge separate and light harvesting process in photosynthetic protein, the artificial photosynthetic system are normally comprised of electron donors and acceptors which linked by covalent bonds or supramolecular interactions.The versatile optical, redox, and photochemical properties of porphyrins makes them ideal substitute for chlorophylls in artificial photosynthetic systems. It is proved to be a good electron donor in the most of D-A arrays as revealed by numerous literature reports. The perylene tetracarboxylic diimide (PDI) has strong absorption between the porphyrin Soret (B) and Q bands, strong emission with high fluorescence quantum yield, and rational fluorescence lifetime. The particular important is its high stabilities toward heat and light. PDIs can be modified easily on the molecular structure, which not only change photophysical and redox properties, as well as improve the solubility of theses compounds in common organic solvents. Very recently, the D-A systems composed of both porphyrin and PDI became the focus of many research groups. However, the D-A systems. containing face-to-face arranged porphyrin dimer and PDI has never been reported so far. In this thesis, we have prepared several D-A systems composed of a porphyrin dimer and a PDI lined by different bridges. Some novel photophysical properties have been found for these compounds. To the best of our knowledge, this represents the first example of the artificial photosynthetic model, which contains porphyrin dimer and PDI at the same time.The photophysical properties of these two compounds were investigated by the steady state electronic absorption and fluorescecne spectra and the lifetime measurements. The ground state absorption spectra revealed intense interactions between the porphyrin units within the porphyrin dimer but no interactions between porphyirn dimer and PDL The fluorescence spectra suggested an efficient energy transfer from PDI to porphyrin accompanied with a less efficient electron transfer from porphyrin to PDI. The energy transfer is not affected by the dimeric structure of porphyrin as well as the linkage between the porphyrin dimer and PDI. But the electron transfer from porphyrin to PDI is significantly affected by either the linkage between the donor and the acceptor or the polarity of the solvents. The dimeric structure of porphyrin unites in these compounds have promoted the electron transfer in non-polar solvent significantly, but not in polar solvents.