Xiao Shengqiang, El-Khouly Mohamed E, Li Yuliang, Gan Zhenhai, Liu Huibiao, Jiang Li, Araki Yasuyuki, Ito Osamu, Zhu Daoben
CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Bejing 100080, China.
J Phys Chem B. 2005 Mar 3;109(8):3658-67. doi: 10.1021/jp045163e.
Synthesis, characterizations, and photophysical properties of new photoactive dyads and triads containing perylenetetracarboxylic diimide (PIm) and porphyrin (free-base porphyrin (H(2)P) and zinc porphyrin (ZnP)), in which both entities were connected with a short ether bond, were examined with the aim of using these systems for molecular photonics. The porphyrin(P)-PIm systems absorbed strongly across the visible region, which greatly matched the solar spectrum. The geometric and electronic structures of the dyads and triads were probed using density function theory method at the B3LYP/3-21G level. It was revealed that the majority of the highest-occupied molecular orbital was located on the porphyrin entity, while the lowest-unoccupied molecular orbitals were entirely on the PIm entity. The excited-state electron-transfer processes were monitored by both steady-state and time-resolved emission as well as transient-absorption techniques in polar solvent benzonitrile. Upon excitation of the P (H(2)P and ZnP) moieties, efficient fluorescence quenching of the P moiety was observed, suggesting that the main quenching paths involved charge separation from the excited singlet porphyrin ((1)P) to the PIm moiety. Upon excitation of the PIm moiety, fluorescence quenching of the (1)PIm moiety was also observed. The nanosecond transience of spectra in near-IR region revealed the charge separation process from the P moieties to the PIm moiety via their excited singlet states. The lifetimes of the charge-separated states were evaluated to be 7-14 ns, depending on the solvent polarity. Photosensitized electron mediation systems were also revealed in the presence of methyl viologen and sacrificial electron donor.
研究了含有苝四羧酸二酰亚胺（PIm）和卟啉（游离碱卟啉（H₂P）和锌卟啉（ZnP））的新型光活性二元体和三元体的合成、表征及光物理性质，其中这两个实体通过短醚键相连，目的是将这些体系用于分子光子学。卟啉（P）-PIm体系在可见光区域有强烈吸收，这与太阳光谱非常匹配。使用密度泛函理论方法在B3LYP/3 - 21G水平上探究了二元体和三元体的几何和电子结构。结果表明，最高占据分子轨道的大部分位于卟啉实体上，而最低未占据分子轨道完全位于PIm实体上。在极性溶剂苄腈中，通过稳态和时间分辨发射以及瞬态吸收技术监测激发态电子转移过程。当激发P（H₂P和ZnP）部分时，观察到P部分的有效荧光猝灭，这表明主要的猝灭途径涉及从激发单重态卟啉（¹P）到PIm部分的电荷分离。当激发PIm部分时，也观察到¹PIm部分的荧光猝灭。近红外区域光谱的纳秒瞬态显示了从P部分到PIm部分通过其激发单重态的电荷分离过程。根据溶剂极性，电荷分离态的寿命评估为7 - 14 ns。在甲基紫精和牺牲电子供体存在的情况下，还揭示了光敏电子介导体系。
