Energy transfer followed by electron transfer in a supramolecular triad composed of boron dipyrrin, zinc porphyrin, and fullerene: A model for the photosynthetic antenna-reaction center complex
Energy transfer followed by electron transfer in a supramolecular triad composed of boron dipyrrin, zinc porphyrin, and fullerene: A model for the photosynthetic antenna-reaction center complex
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DOI：
10.1021/ja030647u
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发表时间：
2004-06-30
影响因子：
15
通讯作者：
Ito, O
中科院分区：
文献类型：
--
作者：
D'Souza, F;Smith, PM;Ito, O
本文报道了通过自组装超分子方法构建的光合天线-反应中心复合物工作模型的第一个例子。为此，通过轴向配位咪唑附加的富勒吡咯烷到共价连接的锌卟啉-硼二吡啶二元体的锌中心来组装超分子三联体。在二吡啶-锌卟啉二元结构中，选择性激发二吡啶部分产生了有效的能量传递(k(ENT)（单重态）= 9.2 x 10(9) s(-1)；Phi（ENT)（单线态）= 0.83）生成单线态激发卟啉锌。在形成超分子三联体后，受激发的锌卟啉导致电子向配位富勒烯有效转移，导致电荷分离态(k(CS)（单重态）= 4.7 x 10(9) s(-1)；Phi（CS)（单重态）= 0.9）。在目前的超分子三联体中，观察到的能量转移随后的电子转移模拟了自然光合作用的事件。在这里，二吡啶硼作为天线叶绿素，吸收光能并在空间上传输到光合反应中心，而从受激发的卟啉锌到富勒烯的电子转移模拟了反应中心的主要事件，电子激发能以电荷分离的形式转化为化学能。本模型系统的重要特点是其相对“简单”，因为利用超分子方法来模拟光合作用相当复杂的“联合天线-反应中心”事件。
The first example of a working model of the photosynthetic antenna-reaction center complex, constructed via self-assembled supramolecular methodology, is reported. For this, a supramolecular triad is assembled by axially coordinating imidazole-appended fulleropyrrolidine to the zinc center of a covalently linked zinc porphyrin-boron dipyrrin dyad. Selective excitation of the boron dipyrrin moiety in the boron dipyrrin-zinc porphyrin dyad resulted in efficient energy transfer (k(ENT)(singlet) = 9.2 x 10(9) s(-1); Phi(ENT)(singlet) = 0.83) creating singlet excited zinc porphyrin. Upon forming the supramolecular triad, the excited zinc porphyrin resulted in efficient electron transfer to the coordinated fullerenes, resulting in a charge-separated state (k(CS)(singlet) = 4.7 x 10(9) s(-1); Phi(CS)(singlet) = 0.9). The observed energy transfer followed by electron transfer in the present supramolecular triad mimics the events of natural photosynthesis. Here, the boron dipyrrin acts as antenna chlorophyll that absorbs light energy and transports spatially to the photosynthetic reaction center, while the electron transfer from the excited zinc porphyrin to fullerene mimics the primary events of the reaction center where conversion of the electronic excitation energy to chemical energy in the form of charge separation takes place. The important feature of the present model system is its relative "simplicity" because of the utilized supramolecular approach to mimic rather complex "combined antenna-reaction center" events of photosynthesis.