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首页> 外文会议>Proceedings vol.2004-12; Electrochemical Society(ECS) Annual Spring Meeting and International Symposium on Fullerenes, Nanotubes, and Carbon Nanoclusters; 20040509-13; San Antonio,TX(US) >Photoinduced Electron Transfer in Porphyrin-Oligothiophene-Fullerene Linked Triads
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Photoinduced Electron Transfer in Porphyrin-Oligothiophene-Fullerene Linked Triads

机译：卟啉-寡噻吩-富勒烯联三联体中的光诱导电子转移。

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摘要

Photoinduced charge-separation (CS) and recombination (CR) processes of porphyrin(H_2P)-oligothiophene(nT)-fullerene(C_(60)) linked triads (H_2P-nT-C_(60), n = 4, 8, and 12), which were designed to reveal the function of nT as a molecular wire for the electron transfer (ET) process, have been investigated by time-resolved fluorescence and absorption spectroscopic methods. By excitation of the H_2P moiety in toluene, ~1H_2P~*-nT-C_(60) showed predominantly the energy transfer (EN) process generating H_2P-nT-~1C_(60)~*, while the CS process was not observed. The EN rate constant depends on the length of nT. In benzonitrile (PhCN) and o-dichlorobenzene (o-DCB), H_2P~+-nT-C_(60)~-was produced from ~1H_2P~*-nT-C_(60). The most energetically stable final CS state was confirmed to be H_2P-nT~+-C_(60)~-, which was produced via the hole-shift process from H_2P~+-nT-C_(60)~-. The rate constant for the CS process from ~1H_2P~*-nT-C_(60) to H_2P~+-nT-C_(60)~- decreased with the length of the nT moiety, indicating that the nT moiety acts as a molecular wire. The small damping factor showed a pronounced solvent polarity effect (0.03 A~(-1) in PhCN and 0.11 A~(-1) in o-DCB), indicating that a long range ET process through the nT moiety is feasible in polar solvent. The final CS state (H_2P-nT~+-C_(60)~-) returned to neutral triad by the CR process between the vicinal electron (radical anion) and hole (radical cation). The lifetime of the CS state showed the solvent polarity effect ranging from 1.5 - 2.4 μs in PhCN to 14-27 μs in o-DCB at room temperature. The longest lifetime (27 μs) was observed with H_2P-8T~+-C_(60)~- in o-DCB. From the temperature dependence of the CR rate constant, the reorganization energies were evaluated to be 0.8 - 1.1 eV for all triads in PhCN and o-DCB.
机译：卟啉（H_2P）-寡噻吩（nT）-富勒烯（C_（60））连接的三单元组（H_2P-nT-C_（60），n = 4、8和12）旨在揭示nT作为电子转移（ET）过程的分子线的功能，已通过时间分辨荧光和吸收光谱法进行了研究。通过激发甲苯中的H_2P部分，〜1H_2P〜* -nT-C_（60）主要显示出生成H_2P-nT-〜1C_（60）〜*的能量转移（EN）过程，而未观察到CS过程。 EN速率常数取决于nT的长度。在苄腈（PhCN）和邻二氯苯（o-DCB）中，由〜1H_2P〜* -nT-C_（60）生成H_2P〜+ -nT-C_（60）〜。能量最稳定的最终CS状态被确认为H_2P-nT〜+ -C_（60）〜-，它是通过空穴转移过程从H_2P〜+ -nT-C_（60）〜-产生的。从〜1H_2P〜* -nT-C_（60）到H_2P〜+ -nT-C_（60）〜-的CS过程的速率常数随nT部分的长度而降低，表明nT部分起着分子的作用线。小阻尼因子显示出明显的溶剂极性效应（PhCN中为0.03 A〜（-1），o-DCB中为0.11 A〜（-1）），表明在极性溶剂中通过nT部分进行长距离ET处理是可行的。最终的CS状态（H_2P-nT〜+ -C_（60）〜-）通过邻位电子（自由基阴离子）和空穴（自由基阳离子）之间的CR过程返回中性三元组。在室温下，CS状态的寿命显示溶剂极性效应在PhCN中为1.5-2.4μs，在o-DCB中为14-27μs。在o-DCB中使用H_2P-8T〜+ -C_（60）〜-可以观察到最长寿命（27μs）。根据CR速率常数的温度依赖性，PhCN和o-DCB中所有三单元组的重组能评估为0.8-1.1 eV。

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