Cyclic Tetramers of Zinc Chlorophylls as a Coupled Light-Harvesting Antenna-Charge-Separation System

Yoshinao Shinozaki; Kei Ohkubo; Shunichi Fukuzumi; Kosuke Sugawa; Joe Otsuki

doi:10.1002/chem.201503789

Cyclic Tetramers of Zinc Chlorophylls as a Coupled Light-Harvesting Antenna-Charge-Separation System

Chemistry. 2016 Jan 18;22(3):1165-76. doi: 10.1002/chem.201503789. Epub 2015 Nov 30.

Authors

Yoshinao Shinozaki¹, Kei Ohkubo^{2

3}, Shunichi Fukuzumi^{4

5

6}, Kosuke Sugawa¹, Joe Otsuki⁷

Affiliations

¹ College of Science and Technology, Nihon University, 1-8-14 Kanda Surugadai, Chiyoda-ku, Tokyo, 101-8308, Japan.
² Department of Material and Life Science, Graduate School of Engineering, ALCA and SENTAN, JST, Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871, Japan.
³ Faculty of Science and Engineering, Meijo University, ALCA and SENTAN, JST, Nagoya, Aichi, 468-0073, Japan.
⁴ Department of Material and Life Science, Graduate School of Engineering, ALCA and SENTAN, JST, Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871, Japan. fukuzumi@chem.eng.osaka-u.ac.jp.
⁵ Department of Bioinspired Science, Ewha Womans University, Seoul, 120-750, Korea. fukuzumi@chem.eng.osaka-u.ac.jp.
⁶ Faculty of Science and Engineering, Meijo University, ALCA and SENTAN, JST, Nagoya, Aichi, 468-0073, Japan. fukuzumi@chem.eng.osaka-u.ac.jp.
⁷ College of Science and Technology, Nihon University, 1-8-14 Kanda Surugadai, Chiyoda-ku, Tokyo, 101-8308, Japan. otsuki.joe@nihon-u.ac.jp.

PMID: 26616389
DOI: 10.1002/chem.201503789

Abstract

A coupled light-harvesting antenna-charge-separation system, consisting of self-assembled zinc chlorophyll derivatives that incorporate an electron-accepting unit, is reported. The cyclic tetramers that incorporated an electron acceptor were constructed by the co-assembly of a pyridine-appended zinc chlorophyll derivative, ZnPy, and a zinc chlorophyll derivative further decorated with a fullerene unit, ZnPyC60 . Comprehensive steady-state and time-resolved spectroscopic studies were conducted for the individual tetramers of ZnPy and ZnPyC60 as well as their co-tetramers. Intra-assembly singlet energy transfer was confirmed by singlet-singlet annihilation in the ZnPy tetramer. Electron transfer from the singlet chlorin unit to the fullerene unit was clearly demonstrated by the transient absorption of the fullerene radical anion in the ZnPyC60 tetramer. Finally, with the co-tetramer, a coupled light-harvesting and charge-separation system with practically 100 % quantum efficiency was demonstrated.

Keywords: chlorophylls; electron transfer; energy transfer; fullerenes; self-assembly.

Publication types

Research Support, Non-U.S. Gov't