Highly pure synthesis, spectral assignments, and two-photon properties of cruciform porphyrin pentamers fused with benzene units.
Highly pure synthesis, spectral assignments, and two-photon properties of cruciform porphyrin pentamers fused with benzene units.
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DOI：
10.1002/chem.200903196
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发表时间：
2010-04
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通讯作者：
Hiroki Uoyama;Kil Suk Kim;Kenji Kuroki;Jae‐Yoon Shin;T. Nagata;T. Okujima;H. Yamada;N. Ono;Dongho Kim;H. Uno
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文献类型：
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作者：
Hiroki Uoyama;Kil Suk Kim;Kenji Kuroki;Jae‐Yoon Shin;T. Nagata;T. Okujima;H. Yamada;N. Ono;Dongho Kim;H. Uno
四聚卟啉形成2-羟甲基吡咯与卟啉通过双环[2.2.2]辛二烯单元融合得到双环[2.2.2]辛二烯融合的卟啉五聚体。五聚体的热转化得到了与苯单元融合的完全共轭的十字型卟啉五聚体。全偶联卟啉五聚体的紫外/可见光谱显示出很强的Q吸收，与普通卟啉有很大的不同。通过TD-DFT计算，HOMO能级比HOMO-1能级高0.49 eV。LUMO和LUMO+1能级非常接近，比其他未占据的MOs低0.27 eV以上。强Q吸收被解释为两个相互正交的单电子跃迁（683nm: 86%, HOMO—>LUMO; 680nm: 86%, HOMO—>LUMO+1）。苯融合卟啉五聚体在1500 nm处的双光子吸收（TPA）横截面值sigma（(2)）为3900 GM，这与具有多向偶联途径的十字形分子结构密切相关。
Tetrameric porphyrin formation of 2-hydroxymethylpyrrole fused with porphyrins through a bicyclo[2.2.2]octadiene unit gave bicyclo[2.2.2]octadiene-fused porphyrin pentamers. Thermal conversion of the pentamers gave fully pi-conjugated cruciform porphyrin pentamers fused with benzene units in quantitative yields. UV/Vis spectra of fully pi-conjugated porphyrin pentamers showed one very strong Q absorption and were quite different from those of usual porphyrins. From TD-DFT calculations, the HOMO level is 0.49 eV higher than the HOMO-1 level. The LUMO and LUMO+1 levels are very close and are lower by more than 0.27 eV than those of other unoccupied MOs. The strong Q absorption was interpreted as two mutually orthogonal single-electron transitions (683 nm: 86 %, HOMO-->LUMO; 680 nm: 86 %, HOMO-->LUMO+1). The two-photon absorption (TPA) cross section value (sigma((2))) of the benzene-fused porphyrin pentamer was estimated to be 3900 GM at 1500 nm, which is strongly correlated with a cruciform molecular structure with multidirectional pi-conjugation pathways.