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Development of Catalytic Process for Photooxidation with Fluorinecontaining Molecules and Their Assemblies

含氟分子及其组装体光氧化催化工艺的研究进展

基本信息

批准号：
05650782
负责人：
WADA Yuji
金额：
$ 1.41万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

1) We succeeded in photo-splitting of water molecule into dihydrogen and hydroxyl radical with Rh-supported perfluoropoly (rho-phenylene) under UV irradiation. Hydroxyl radical formed via one-electron oxidation of water molecule is captured by benzene molecule in the reaction system, resulting in formation of phenol. The amount of H_2 evolved in the system is half of that expected from the amount of phenol formed and the reaction stoicheometry. It is due to consumption of electrons in the decomposition of perfluoropoly (rho-phenylene) through its radical anion and reduction of benzene. Molecular orbital calculations show that a water molecule interacts with fluorinated phenylene ring, suggesting an important role of the attractive interaction in the photooxidation of water.2) Laser flash photlysis was carried out in order to reveal the mechanism of photooxidation of water with perfluorooligo (rho-phenylene) as a photocatalyst. The excited state of perfluorooligo (rho-phenylene) is readily converted to triplet stated through intersystem crossing. It is proposed that the triplet state of perfluorooligo (rho-phenylene) is oxidatively quenched to be converted to its cation radical, which acts as an oxidizing species of water molecule.3) The cyclic voltammetry measurements of partially fluorinated oligo (rho-phenylene) have shown that the reduction and oxidation potentials shifts to the positive side with increase in the degree of fluorination.4) Octafluorophenazine was sythesized. This compound induces one-electron oxidation of water under visible light irradiation.

1)在紫外光照射下，我们成功地实现了Rh负载的全氟多聚(Rho-Ph)光分解水分子生成氢和羟基的反应。水分子单电子氧化生成的羟基自由基被反应体系中的苯分子捕获，生成苯酚。体系中析出的氢气量是苯酚生成量和反应化学计量比所预期的一半。这是由于全氟多聚物(Rho-Phenene)通过其自由基阴离子分解和苯的还原消耗了电子。分子轨道计算表明，水分子与含氟苯环相互作用，表明这种吸引相互作用在水的光氧化反应中起着重要作用。2)为了揭示全氟齐聚物作为光催化剂的水的光氧化反应机理，进行了激光闪光光解。全氟齐聚物的激发态通过系间交叉很容易转变为三重态。提出了全氟齐聚物的三重态被氧化猝灭转化为阳离子自由基，从而成为水分子的氧化物种。3)部分氟化齐聚物的循环伏安测试表明，随着氟化度的增加，还原和氧化电位向正极移动。4)合成了八氟吩嗪。这种化合物在可见光照射下能诱导水的单电子氧化。