Substituent effects of porphyrin monolayers on the structure and photoelectrochemical properties of self-assembled monolayers of porphyrin on indium-tin oxide electrode
Substituent effects of porphyrin monolayers on the structure and photoelectrochemical properties of self-assembled monolayers of porphyrin on indium-tin oxide electrode
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DOI：
10.1021/jp037625e
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发表时间：
2004-04-22
影响因子：
3.3
通讯作者：
Matano, Y
中科院分区：
文献类型：
--
作者：
Imahori, H;Hosomizu, K;Matano, Y
制备了卟啉的自组装单层 (SAM)，以研究卟啉单层的取代基对 ITO 电极上 SAM 的结构和光电化学性质的影响。卟啉 SAM 的紫外（UV）-可见光吸收、稳态荧光和循环伏安测量表明，不带大叔丁基的卟啉之间的相互作用比具有大叔丁基的卟啉大得多。使用修饰的 ITO 工作电极、铂丝对电极和 Ag/AgCl 参比电极，在含有三乙醇胺作为电子牺牲剂的氮饱和 Na2SO4 水溶液中进行光电化学测量。无论空间位阻如何，光电流产生的内部量子产率和卟啉荧光寿命几乎保持不变，这与传统分子组装体（例如 Langmuir-Blodgett 薄膜）中卟啉激发单线态的严重自猝灭形成鲜明对比。 SAM 中卟啉的二维致密结构负责长寿命的激发单线态，这类似于蓝细菌中光系统 I 的天线功能。这些结果将为人工光采集系统的构建提供有价值的信息。
Self-assembled monolayers (SAMs) of porphyrins have been prepared to examine the substituent effects of porphyrin monolayers on the structure and photoelectrochemical properties of the SAMs on an ITO electrode. The ultraviolet (UV)-visible absorption, steady-state fluorescence, and cyclic voltammetry measurements for the porphyrin SAMs revealed that the interaction between the porphyrins without bulky tert-butyl groups is much larger than that of the porphyrins with bulky tert-butyl groups. Photoelectrochemical measurements were performed in nitrogen-saturated Na2SO4 aqueous solution containing triethanolamine as an electron sacrificer using the modified ITO working electrode, a platinum wire counter electrode, and an Ag/AgCl reference electrode. The internal quantum yields of photocurrent generation together with the porphyrin fluorescence lifetimes rernain virtually the same irrespective of the steric hindrance, which is in sharp contrast with severe self-quenching of the porphyrin excited singlet state in conventional molecular assemblies such as Langmuir-Blodgett films. The two-dimensional, densely packed structure of the porphyrins in SAM is responsible for the long-lived excited singlet state, which is similar to the antenna function of photosystem I in cyanobacteria. These results will provide valuable information on the construction of artificial light-harvesting systems.