Giant porphyrin wheels with large electronic coupling as models of light-harvesting photosynthetic antenna.
Giant porphyrin wheels with large electronic coupling as models of light-harvesting photosynthetic antenna.
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DOI：
10.1002/chem.200501373
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发表时间：
2006-02
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通讯作者：
Takaaki Hori;N. Aratani;Akihiko Takagi;T. Matsumoto;T. Kawai;Min-Chul Yoon;Z. S. Yoon;Sung Cho;Dongho Kim;A. Osuka
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文献类型：
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作者：
Takaaki Hori;N. Aratani;Akihiko Takagi;T. Matsumoto;T. Kawai;Min-Chul Yoon;Z. S. Yoon;Sung Cho;Dongho Kim;A. Osuka
从 1,3-亚苯基连接的二卟啉锌 (II) 络合物 2ZA 开始，重复逐步 Ag(I) 促进的偶联反应提供线性低聚物 4ZA、6ZA、8ZA 和 12ZA。 12ZA在稀条件(1×10(-6)M)下进行分子内环化反应，得到直径约为35 A的卟啉环C12ZA，收率60％。该合成策略已应用于 1,3-亚苯基连接的四卟啉 4ZB，以提供 8ZB、12ZB、16ZB、24ZB 和 32ZB。 24ZB的分子内偶联反应得到更大的24聚体卟啉环C24ZB，直径约为70埃，产率34%。通过 1H NMR 光谱、基质辅助激光解吸电离飞行时间 (MALDI-TOF) 质谱、紫外可见光谱、凝胶渗透色谱 (GPC) 分析和扫描隧道显微镜 (STM) 技术对这两个大卟啉环进行了表征。 C12ZA 的 STM 图像显示主要为圆形结构，而 C24ZB 的 STM 图像主要显示椭圆形形状，表明 C24ZB 具有更大的构象灵活性。与 C12ZA 的情况类似，通过使用时间相关单光子计数 (TCSPC) 和皮秒瞬态吸收各向异性 (TAA) 测量，C24ZB 已证实沿环的有效激发能量转移，并且相邻四卟啉亚基之间的能量跳跃速率为 (35 ps)(-1)。总的来说，目前的工作为构建具有充足电子相互作用的大型循环排列卟啉阵列作为光捕获天线模型提供了重要的一步。
Starting from a 1,3-phenylene-linked diporphyrin zinc(II) complex 2ZA, repeated stepwise Ag(I)-promoted coupling reactions provided linear oligomers 4ZA, 6ZA, 8ZA, and 12ZA. The intramolecular cyclization reaction of 12ZA under dilute conditions (1x10(-6) M) gave porphyrin ring C12ZA with a diameter of approximately 35 A in 60% yield. This synthetic strategy has been applied to a 1,3-phenylene-linked tetraporphyrin 4ZB to provide 8ZB, 12ZB, 16ZB, 24ZB, and 32ZB. The intramolecular coupling reaction of 24ZB gave a larger 24-mer porphyrin ring C24ZB with a diameter of approximately 70 A in 34% yield. These two large porphyrin rings were characterized by means of 1H NMR spectroscopy, matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectroscopy, UV-visible spectroscopy, gel permeation chromatography (GPC) analysis, and scanning tunneling microscopy (STM) techniques. The STM images of C12ZA reveal largely circular structures, whereas those of C24ZB exhibit mostly ellipsoidal shapes, indicating more conformational flexibility of C24ZB. Similar to the case of C12ZA, the efficient excitation energy transfer along the ring has been confirmed for C24ZB by using the time-correlated single-photon counting (TCSPC) and picosecond transient absorption anisotropy (TAA) measurements, and occurs with a rate of (35 ps)(-1) for energy hops between neighboring tetraporphyrin subunits. Collectively, the present work provides an important step for the construction of large cyclic-arranged porphyrin arrays with ample electronic interactions as a model of light-harvesting antenna.