Ultrafast Electron Transfer Dynamics of Directly Linked Porphyrin-Electron Acceptor Dyads

直接连接的卟啉-电子受体二元体的超快电子转移动力学

• 批准号: 14540481
• 负责人: TANIGUCHI Seiji
• 金额: $ 1.98万
• 依托单位: Institute for Laser Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14540481/
• 关键词: Femtosecond Fluorescence Dynamics; Porphyrin-Electron Acceptor Dyads; S_2 Fluorescence; Photoinduced Electron Transfer; Energy Gap Dependence; Medium Effect; 蛍光アップコンバージョン; 溶媒効果

We have investigated the photoinduced electron transfer processes from S_2 excited states of directly linked Zinc porphyrin-imide (ZP-Im) dyads and its solvent effects by using femtosecond fluorescence up-conversion method with 〜120fs time resolution. The S_2 fluorescence lifetime changed from 〜130fs to 〜800fs with the species of imide. The energy gap dependence of the charge separation rate constants (k_<CS>) calculated form S_2 fluorescence lifetimes showed obvious "bell shapes" in low polar solvents (methylcyclohexane and toluene). S_2 fluorescence dynamics in polystyrene film were measured for the research of solvent viscosity effects. The energy gap dependence of k_<CS> was nearly the same with those in other solvents (like as toluene), which shows the ultrafast electron transfer from S_2 state can occurs even in the case that the freedom of the dynamic motion of the solvents around are restricted. In alcohol (ethanol and butanol) solutions, k_<CS> were larger than those in other solutions in the normal region, which caused by the hydrogen-bond interaction between ZIP-Im and the solvents. We have also measured the S_1 fluorescence dynamics with S_2 state excitation. In THF the lifetimes of S_1 state conversion (S_1 fluorescence rise) corresponded to the S_2 fluorescence decays, but in toluene and methylcyclohexane they were larger for 〜150fs than the S_2 fluorescence decays in top region. These results show that the S_1state conversion mainly caused by the back electron transfer reaction from the charge separation state and the rates of back electron transfer smaller than the charge separation rates from S_2 state. The S_2 fluorescence dynamics of directly linked ZP-quinone dyads were also investigated, and ultrafast electron transfer with 〜130fs lifetimes were also observed.

利用飞秒荧光上转换技术研究了直接连接的锌卟啉-亚胺（ZP-Im）二元体系S_2激发态的光诱导电子转移过程及其溶剂效应。S_2荧光寿命随酰亚胺种类的不同而变化，从130 fs到800 fs。在<CS>低极性溶剂（甲基环己烷和甲苯）中，由S_2荧光寿命计算的电荷分离速率常数（k_）与能隙的关系呈明显的“钟形”。为了研究溶剂粘度效应，测量了聚苯乙烯薄膜中S_2的荧光动力学。k_1与能隙的关系<CS>与其它溶剂（如甲苯）中的k_1与能隙的关系基本相同，说明即使在限制周围溶剂动力学运动自由度的情况下，也能发生从S_2态的超快电子转移。在醇（乙醇和丁醇）溶液中，在正常范围内，ZIP-Im的k值<CS>比其它溶液中的k值大，这是由于ZIP-Im与溶剂之间的氢键作用造成的。我们还测量了S_2态激发下的S_1荧光动力学。在四氢呋喃中，S_1态的转换寿命（S_1荧光的上升）对应于S_2荧光的衰减，而在甲苯和甲基环己烷中，在150 fs处，它们大于顶部区域的S_2荧光衰减。结果表明，S_1态的转变主要是由电荷分离态的背电子转移反应引起的，背电子转移速率小于S_2态的电荷分离速率。研究了直接键合的ZP-quinone二联体的S_2荧光动力学，并观察到了寿命为130 fs的超快电子转移。

项目成果

Noboru Mataga: "Ultrafast Charge Separation and Radiationless Relaxation Processes from Higher Excited Electronic States of Directly Linked Porphyrin-Acceptor Dyads"Photochemical & Photobiological Sciences. 2. 493-500 (2003)

Noboru Mataga：“直接连接的卟啉受体二元体的更高激发电子态的超快电荷分离和无辐射弛豫过程”光化学

Noboru Mataga: "Ultrafast Charge Separation and Radiationless Relaxation Processes from Higher Excited Electronic States of Directly Linked Porphyrin-Acceptor Dyads"Photochemical & Photobiological Sciences. (in press). (2003)

Noboru Mataga：“直接连接的卟啉受体二元体的更高激发电子态的超快电荷分离和无辐射弛豫过程”光化学

Seiji Taniguchi: "Ultrafast Charge Separation and Radiationless Relaxation Processes From S_2 Excited Electronic States of Directly Linked Zinc-Porphyrin-Acceptor Dyads"Femto-chemistry and Femtobiology : Ultrafast Events in Molecular Science (published by

Seiji Taniguchi：“直接连接的锌-卟啉-受体二元体的 S_2 激发电子态的超快电荷分离和无辐射弛豫过程”飞秒化学和飞秒生物学：分子科学中的超快事件（由

Noboru Mataga, Haik Chosrowjan, Seiji Taniguchi, Yutaka Shibata, Atsuhiro Osuka, Naoya Yoshida, Takeshi Kikuzawa, Tadashi Okada: "Ultrafast Charge Separation from the S_2 Excited State of Directly Linked Porphyrin-Imide Dyads : First Unequivocal Observati

Noboru Mataga、Haik Chosrowjan、Seiji Taniguchi、Yutaka Shibata、Atsuhiro Osuka、Naoya Yoshida、Takeshi Kikuzawa、Tadashi Okada：“直接连接的卟啉-酰亚胺二元组的 S_2 激发态的超快电荷分离：首次明确的观察

Noboru Mataga, Seiji Taniguchi, Haik Chosrowjan, Atsuhiro Osuka, Naoya Yoshida: "Ultrafast Charge Separation and Radiationless Relaxation Processes from Higher Excited Electronic States of Directly Linked Porphyrin-Acceptor Dyads"Photochemical and Photobi

Noboru Mataga、Seiji Taniguchi、Haik Chosrowjan、Atsuhiro Osuka、Naoya Yoshida：“直接连接的卟啉受体二元组的更高激发电子态的超快电荷分离和无辐射弛豫过程”光化学和光双