【作者】 陶敏莉；

【导师】 刘东志；

【作者基本信息】 天津大学 ， 应用化学， 2007， 博士

【摘要】 卟啉类化合物构成叶绿素等生物大分子的核心部分,作为原初电子给体参与植物光合作用的一系列重要过程,因此也是模拟光合作用的重要化合物。在光合作用中,物质的转换和能量的的储备仅是宏观现象,而光反应中心电荷分离态的形成和电子的传递是决定这一过程的微观因素。因此建立光合作用模型化合物,研究其分子内部电子传递及电荷分离态的形成成为学者们研究的热点,本文即以卟啉类化合物为光敏体,通过引入不同性质的连接基团,设计合成了系列模型化合物,研究其分子内电子、能量传递情况及电荷分离态的形成。为进一步实现对光合作用PSII的模拟奠定了理论基础。自然界的光合作用以醌类化合物为原初电子受体,因此以醌类化合物作为电子受体建立模型化合物模拟绿色植物光合作用成为研究工作者们的首选。蒽醌类化合物为良好的电子受体,并且其结构与自然界光合作用电子受体的结构接近。因此本文以卟啉类化合物为光敏体,蒽醌类化合物为电子受体,设计合成了14种未见文献报道的新型卟啉-蒽醌模型化合物,分别为偶氮卟啉-蒽醌化合物（4）、以均三嗪为桥键的卟啉-蒽醌化合物（4）、以酰氨键相连的卟啉-蒽醌化合物（2）、以烷基链相连的卟啉-蒽醌化合物（2）及相应的金属络合物（2）。采用红外,核磁,质谱等分析手段对合成化合物进行结构表征,并用单晶衍射确定化合物46的分子结构。对化合物的光电性能进行了系统研究。荧光光谱表明合成的卟啉-蒽醌二元化合物均发生光诱导的分子内电子传递导致化合物的荧光猝灭,其中以化合物6为最大,猝灭百分率达到95%。采用时间分辨光致荧光光谱测定化合物46固态荧光寿命为315ps,荧光寿命的大幅度降低进一步表明卟啉-蒽醌体系中发生了分子内的电子传递。采用闪光光解光谱仪对合成化合物的瞬态光谱性能进行了测定。实验结果表明化合物27, 34在600nm, 650nm处出现卟啉阳离子自由基P^·+的特征吸收,这是由于体系中发生了光诱导的分子内电子传递,形成P^·+-AQ^·-的长寿命电荷分离态,改变了激发态电子运动途径所致。动力学衰减曲线拟合的电荷分离态寿命分别为1.42μs和1.33μs。较长寿命的电荷分离态P^·+-AQ^·-的形成,为进一步优化二元化合物体系提供了理论指导和基本思路,并且形成的电荷分离态的结构更接近自然界,因此化合物27, 34为性能优良的PSⅡ模型化合物设计合成了9种未见文献报道的新型卟啉-噁二唑模型化合物,分别为偶氮卟啉-噁二唑化合物（6）、以均三嗪为桥键的卟啉-噁二唑化合物（3）。采用红外,核磁,质谱等分析手段对合成化合物进行结构表征。通过MM2对分子进行简单的模拟计算,确定化合物22, 23, 36b的分子结构。核磁氢谱和红外光谱表明偶氮羟基卟啉-噁二唑化合物21, 22, 43, 44中存在着偶氮体和醌腙体的互变异构。化合物的光谱性能表明在卟啉-噁二唑二元化合物36b, 36c, 23, 37中,发生了由激发态噁二唑基团至卟啉基团的能量传递,导致噁二唑基团荧光猝灭,卟啉基团荧光增强。不存在分子内卟啉基团向噁二唑基团的电子回传竞争。此外,氧化还原性能的计算表明卟啉基团的最低空轨道和最高占据轨道夹在噁二唑的最低空轨道和最高占据轨道之间,因而可能发生从噁二唑基团向卟啉基团的电子传递。因此卟啉-噁二唑二元化合物可能成为模拟PSⅡ中电子给体方的优良模型化合物。以4,4’-二甲基-2,2’-联吡啶为原料,经NBS溴化,在强碱的作用下,与羟基卟啉TNPPOH发生烷基化反应,设计合成了以醚键相连的卟啉-联吡啶二元化合物35。以4,4’-二甲基-2,2’-联吡啶为原料,经二氧化锡,氧化银分步氧化,氯化亚砜氯化,再与氨基卟啉ATPP发生酰化反应生成以酰胺键相连的卟啉-联吡啶二元化合物38。采用核磁,质谱等分析手段对合成化合物进行结构表征确定。并对化合物35进行了稳态光谱性能、瞬态光谱性能及氧化还原性能的测试,为进一步建立卟啉-联吡啶锰络合物的模型化合物奠定了基础。采用Fmoc保护氨基酸,氯化亚砜对被保护的氨基酸中羧基进行活化,将氨基酸基团引入卟啉体系,设计合成了11种未见文献报道的新型卟啉-氨基酸二元化合物,分别为以酰氨键相连的卟啉-氨基酸化合物（6）、以酯键相连的卟啉-氨基酸化合物（5）;设计合成了2种未见文献报道的新型卟啉-氨基酸三元化合物。采用红外,核磁,质谱等分析手段对合成化合物进行结构表征确定。对合成化合物进行了稳态光谱性能、瞬态光谱性能及氧化还原性能测试,为进一步建立含有氨基酸基团的卟啉-联吡啶锰络合物的模型化合物奠定了基础。另外,在合成以酯键相连的卟啉-氨基酸化合物时,得到了含有两个氨基酸链节的化合物17, 20, 29, 30,对其反应机理进行了探讨研究。更多还原

【Abstract】 Porphyrins and their relatives are the cores of chlorophyll molecules. As the primary electron donor, they participate in a series of important process in photosynthesis. So porphyrins are the significant compounds in artificial photosynthesis. In nature photosythesis, the substance conversion and energy storage are only macroscopical phenomena, but the formation of charge-separation state and electron transfer are the determinative factors. Therefore building model compounds to investigate on the intramolecular electron transfer and charge-separated state formation attracted considerable attention of scholar. In this dissertation, a series of PSⅡmodel compounds with porphyrins as photosensitizer were design and synthesis, and the intramolecular electron and energy transfer and charge-separated state formation were studied to make theory foundation for the further modeling of PSⅡ.Quinone compound are the primary electron acceptor in nature photosynthesis, thus building model compounds of artificial photosynthesis with quinone as acceptor is the first selection to the scholar. In the dissertation, model compounds were built with porphyrin(P) as electron donor and anthraquinone(AQ) as acceptor. Firstly, a series of asymmetry porphyrins were synthesized, then 14 novel porphyrin- anthraquinone dyads were designed, synthesized and characterized by IR, 1H NMR and MS. They respectively connected with azo bond, with cyanuric chloride as bridge, with amido bond, with alkyl chain. Secondly, the photoelectric properties of the new compounds were studied in details. Fluorescence quenching of the dyads exhibit that intramolecular photoinduced electron transfer occurred in the porphyrin- anthraquinone molecules. And the great decrease of fluorescence lifetime (315ps) of compound 46 further confirms this. The P·+-AQ·-state can be observed by transient absorption spectroscopy because the absorption spectrum of the charge-separated state differs from that of the porphyrin excited triplet in 600~700nm. The experiment results of transient absorption spectroscopy illustrated that new absorption band appeared at 600nm and 650nm due to the formation of porphyrin cation in compounds 27, 34. The lifetime of charge-separated state is 1.42μs and 1.33μs respectively. The formation of long-lived charge-separated state provides theory guidance and essential idea for the optimization of dyads system. And the structure of the charge-separated state is more close to the nature. So porphyrin-anthraquinone dyads 27 and 34 are excellent PSII model compounds. 9 novel porphyrin-oxadiazole dyads connected with azo bond and with cyanuric chloride as bridge were designed, synthesized and characterized by IR, 1H NMR and MS. The molecular structures of compounds 22, 23, 36b were further identified through MM2 simulating calculation. The spectral properties of new dyads were investigated in details. The experiment results show that intramolecular photoinduced energy transfer occurred from excited oxadiazole moiety to porphyrin moiety in the dyads 36b, 36c, 23 and 37, leading to the fluorescence quenching of oxadiazole moiety and the fluorescence enhancing of porphyrin moiety. And there is no return electron transfer from excited porphyrin moiety to oxadiazole moiety. Moreover, the results obtained from the redox property indicated that the HOMO and LUMO of porphyrin moiety sandwiched between the levels of the HOMO and LUMO of oxadiazole moiety. So electron transfer from oxadiazole moiety to porphyrin moiety becomes possible. The porphyrin-oxadiazole dyads will be the fine PSII model compounds.4,4’-dimethyl-2,2’-bipyridine reacted with NBS, then alkylation with hydroxyl porphyrin at the existence of NaOH to generated porphyrin-bipyridine dyad 35. Porphyrin-bipyridine dyad 38 was prepared from amino porphyrin and 4-dimethyl-4’-carboxylchlroride-2,2’-bipyridine. The structures of new compounds were confirmed by 1H NMR and MS. And the photoelectric property of compound 35 was studied to make foundation for the further synthesis of porphyrin-bipyridine-Mn model compounds.11 novel porphyrin-aminoacid dyads and 2 triads were prepared from porphyrin and amino acid through protection of amino group of amino acid with Fmoc-OSu, then activation of carboxyl group with SOCl2, and characterized by IR, 1H NMR and MS. The photoelectric properties of compounds were studied in detail to make foundation for the further synthesis of porphyrin-bipyridine-Mn model compounds containing amino acid moiety. In addition the reaction mechanism of compounds 17, 20, 29, 30, which synthesized through esterification and included two amino acid chains, was discussed.更多还原