Selective inclusion of electron-donating molecules into porphyrin nanochannels derived from the self-assembly of saddle-distorted, protonated porphyrins and photoinduced electron transfer from guest molecules to porphyrin dications.
Selective inclusion of electron-donating molecules into porphyrin nanochannels derived from the self-assembly of saddle-distorted, protonated porphyrins and photoinduced electron transfer from guest molecules to porphyrin dications.
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DOI：
10.1002/chem.200601654
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发表时间：
2007-10
期刊：
影响因子：
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通讯作者：
Takahiko Kojima;Tatsuaki Nakanishi;Ryosuke Harada;K. Ohkubo;S. Yamauchi;S. Fukuzumi
中科院分区：
文献类型：
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作者：
Takahiko Kojima;Tatsuaki Nakanishi;Ryosuke Harada;K. Ohkubo;S. Yamauchi;S. Fukuzumi
鞍形畸变十二苯基卟啉（H2DPP）的双质子化盐酸盐[H4DPPP] Cl2形成卟啉纳米通道（PNC）。X射线晶体学用于确定分子的结构，其揭示了PNC内包含客体分子。给电子分子，如对苯二酚和对二甲苯，选择性地包括在PNC内，与电子受体形成鲜明对比，如相应的醌类，其未被封装。这一结果表明，PNC在包结过程中可以识别客体分子的电子性质和空间位阻。含有对苯二酚、邻苯二酚和对苯二酚客体分子的PNC的ESR测量（在室温下在λ> 340 nm处的光照射）给出了良好分辨的信号，基于ESR光谱的计算机模拟和密度泛函理论（DFT）计算的结果，这些信号被分配给在没有去质子化的情况下形成的阳离子自由基。自由基来自于从客体分子到H4DPP2+的单重态的光诱导电子转移。通过飞秒激光闪光光解的瞬态吸收光谱使我们能够观察到1（H4DPP 2+）* 的形成，其转化为H4DPP+。通过电子从客体分子转移到1（H4DPP 2+）*，然后通过H4DPP+的快速反离子化，和电荷复合，分别得到抗磁性物质和三重激发态3（H4DPP2+）*。
A doubly protonated hydrochloride salt of a saddle-distorted dodecaphenylporphyrin (H2DPP), [H4DPPP]Cl2, forms a porphyrin nanochannel (PNC). X-ray crystallography was used to determine the structure of the molecule, which revealed the inclusion of guest molecules within the PNC. Electron-donating molecules, such as p-hydroquinone and p-xylene, were selectively included within the PNC in sharp contrast to electron acceptors, such as the corresponding quinones, which were not encapsulated. This result indicates that the PNC can recognize the electronic character and steric hindrance of the guest molecules during the course of inclusion. ESR measurements (photoirradiation at lambda>340 nm at room temperature) of the PNC that contains p-hydroquinone, catechol, and tetrafluorohydroquinone guest molecules gave well-resolved signals, which were assigned to cation radicals formed without deprotonation based on results from computer simulations of the ESR spectra and density functional theory (DFT) calculations. The radicals are derived from photoinduced electron transfer from the guest molecules to the singlet state of H4DPP2+. Transient absorption spectroscopy by femtosecond laser flash photolysis allowed us to observe the formation of 1(H4DPP2+)*, which is converted to H4DPP+. by electron transfer from the guest molecules to 1(H4DPP2+)*, followed by fast disproportionation of H4DPP+., and charge recombination to give diamagnetic species and the triplet excited state 3(H4DPP2+)*, respectively.