Comparative photophysical properties of free-base, bis-Zn(II), bis-Cu(II), and bis-Co(II) doubly N-confused hexaphyrins(1.1.1.1.1.1).
Comparative photophysical properties of free-base, bis-Zn(II), bis-Cu(II), and bis-Co(II) doubly N-confused hexaphyrins(1.1.1.1.1.1).
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DOI：
10.1021/jp056083t
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发表时间：
2006-06
期刊：
影响因子：
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通讯作者：
J. Kwon;T. Ahn;Min-Chul Yoon;Deok Yun Kim;M. Koh;Dongho Kim;H. Furuta;Masaaki Suzuki;A. Osuka
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文献类型：
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作者：
J. Kwon;T. Ahn;Min-Chul Yoon;Deok Yun Kim;M. Koh;Dongho Kim;H. Furuta;Masaaki Suzuki;A. Osuka
我们利用时间分辨荧光、飞秒瞬态吸收、双光子吸收测量和几何优化的从头算方法对一系列双金属双氮杂六卟啉（1.1.1.1.1.1）的量子物理进行了比较研究。与卟啉相比，双锌（II）和游离碱双氮杂六卟啉具有良好的分辨和红移的类B和类Q吸收带。在B3 LYP/6- 31 G水平上，通过从头计算得到的HOMO和LUMO前线轨道，证实了它们的允许跃迁是六卟啉环的（pi，pi）跃迁.另一方面，双-Cu（II）和双-Co（II）的双N-混乱的hexaphyrins的吸收光谱是相对较宽的，大概是由于大的耦合之间的金属d-轨道和π-电子的hexaphyrin环。由于这些耦合，bis-Cu（II）和bis-Co（II）的双N-混乱的六卟啉有更短的激发态寿命的9.4 +/- 0.3 ps和670 fs，分别比那些（267 +/- 16和62.4 +/- 1.2 ps，分别）的bis-Zn（II）和游离碱的双N-混乱的六卟啉。双光子吸收截面（σ（2））值，这被认为是强烈依赖于环平面性（π共轭），是在激发态寿命的趋势。
We have comparatively investigated the photophysics of a series of bis-metal doubly N-confused hexaphyrins(1.1.1.1.1.1) using time-resolved fluorescence, femtosecond transient absorption, two-photon absorption measurements, and geometry-optimized ab initio calculations. Bis-Zn(II) and free-base doubly N-confused hexaphyrins exhibit well-resolved and red-shifted B- and Q-like absorption bands compared with porphyrins. Their allowed transitions are (pi,pi) transitions of the hexaphyrin ring, as confirmed by the HOMO and LUMO frontier orbitals based on ab initio calculations at the B3LYP/6-31G level. On the other hand, the absorption spectra of bis-Cu(II) and bis-Co(II) doubly N-confused hexaphyrins are relatively broad, presumably due to large couplings between the metal d-orbitals and pi-electrons of the hexaphyrin ring. Owing to these couplings, bis-Cu(II) and bis-Co(II) doubly N-confused hexaphyrins have much shorter excited-state lifetimes of 9.4 +/- 0.3 ps and 670 fs, respectively, than those (267 +/- 16 and 62.4 +/- 1.2 ps, respectively) of bis-Zn(II) and free-base doubly N-confused hexaphyrins. The two-photon absorption cross section (sigma(2)) values, which are believed to depend strongly on the ring planarity (pi-conjugation), are in line with the excited-state lifetime trends.