Enhanced intersystem crossing due to long-range exchange interaction in copper(II) porphyrin-free base porphyrin dimers: HOMO and spacer dependence

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• 作者：Motoko S. Asano^a ; ^{motoko@tmu.ac.jp} ; Kazuma Okamura^b ; Akihoro Jin-mon^b ; Sadaharu Takahashi^b ; Youkoh Kaizu^b
• 关键词：Photoexcited state ; Unpaired electron ; Long-range coupling ; Superexchange ; Fluorescence
• 刊名：Chemical Physics
• 出版年：2013
• 出版时间：20 June, 2013
• 年：2013
• 卷：419
• 期：Complete
• 页码：250-260
• 全文大小：1007 K

文摘

Photodynamics induced by long-range exchange interaction was studied in two series of copper(II) porphyrin - free base porphyrin dimers linked via an aromatic spacer: one has a_2u orbital as HOMO in the porphyrin ¦Ð-system and the other has a_1u orbital. Dependence on the HOMO as well as that on the spacer is presented for enhanced intersystem crossing (EISC) occurring in the free base half due to long-range coupling with the copper unpaired electron. Semilogarithmic plots of EISC rates vs. number of bonds show a linear correlation in each series of dimers. It was found that the two correlation lines show the same slope but different intercepts. This clearly indicates that electronic communication within the linkage does not depend on the terminal chromophore, while the terminal ¦Ð-system affects the magnitude of EISC rates. Separately, a general expression for EISC rate, involving coupling between the terminal and linkage, was derived theoretically.