Preparation and Photophysical and Photoelectrochemical Properties of a Covalently Fixed Porphyrin–Chemically Converted Graphene Composite |
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| Authors: | Dr. Tomokazu Umeyama Junya Mihara Noriyasu Tezuka Prof. Dr. Yoshihiro Matano Kati Stranius Dr. Vladimir Chukharev Prof. Dr. Nikolai V. Tkachenko Prof. Dr. Helge Lemmetyinen Dr. Kei Noda Prof. Dr. Kazumi Matsushige Prof. Dr. Tetsuya Shishido Dr. Zheng Liu Kaori Hirose‐Takai Prof. Dr. Kazu Suenaga Prof. Dr. Hiroshi Imahori |
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| Affiliation: | 1. Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo‐ku, Kyoto 615‐8510 (Japan), Fax: (+81)?75‐383‐2571;2. PRESTO Japan Science and Technology Agency (JST), 4‐1‐8 Honcho, Kawaguchi, Saitama 332‐0012 (Japan);3. Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, 33101 Tampere (Finland), Fax: (+358)?3‐3115‐2108;4. Department of Electronic Science and Engineering, Graduate School of Engineering, Kyoto University, Nishikyo‐ku, Kyoto 615‐8510 (Japan);5. National Institute of Advanced Industrial, Science and Technology (AIST), AIST Central 5, Tsukuba, 305‐8565 (Japan);6. Institute for Integrated Cell‐Material Sciences (WPI iCeMS), Kyoto University, Nishikyo‐ku, Kyoto 615‐8510 (Japan);7. Fukui Institute for Fundamental Chemistry, Kyoto University, Sakyo‐ku, Kyoto 606‐8103 (Japan) |
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| Abstract: | Chemically converted graphene (CCG) covalently linked with porphyrins has been prepared by a Suzuki coupling reaction between iodophenyl‐functionalized CCG and porphyrin boronic ester. The covalently linked CCG–porphyrin composite was designed to possess a short, rigid phenylene spacer between the porphyrin and the CCG. The composite material formed stable dispersions in DMF and the structure was characterized by spectroscopic, thermal, and microscopic measurements. In steady‐state photoluminescence spectra, the emission from the porphyrin linked to the CCG was quenched strongly relative to that of the porphyrin reference. Fluorescence lifetime and femtosecond transient absorption measurements of the porphyrin‐linked CCG revealed a short‐lived porphyrin singlet excited state (38 ps) without yielding the porphyrin radical cation, thereby substantiating the occurrence of energy transfer from the porphyrin excited state to the CCG and subsequent rapid decay of the CCG excited state to the ground state. Consistently, the photocurrent action spectrum of a photoelectrochemical device with a SnO2 electrode coated with the porphyrin‐linked CCG exhibited no photocurrent response from the porphyrin absorption. The results obtained here provide deep insight into the interaction between graphenes and π‐conjugated systems in the excited and ground states. |
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| Keywords: | energy transfer graphene photophysics porphyrinoids time‐resolved spectroscopy |
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