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Preparation and Photophysical and Photoelectrochemical Properties of a Covalently Fixed Porphyrin–Chemically Converted Graphene Composite
Author(s) -
Umeyama Tomokazu,
Mihara Junya,
Tezuka Noriyasu,
Matano Yoshihiro,
Stranius Kati,
Chukharev Vladimir,
Tkachenko Nikolai V.,
Lemmetyinen Helge,
Noda Kei,
Matsushige Kazumi,
Shishido Tetsuya,
Liu Zheng,
HiroseTakai Kaori,
Suenaga Kazu,
Imahori Hiroshi
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201103843
Subject(s) - porphyrin , photochemistry , covalent bond , excited state , ultrafast laser spectroscopy , photocurrent , chemistry , graphene , materials science , spectroscopy , nanotechnology , organic chemistry , optoelectronics , physics , quantum mechanics , nuclear physics
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 SnO 2 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.