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Reversible photoredox switching of porphyrin-pridged Bis-2,6-di-tert-butylphenols
journal contribution
posted on 2014-08-15, 11:27 authored by Shinsuke Ishihara, Jonathan P. Hill, Atsuomi Shundo, Gary J. Richards, Jan Labuta, Kei Ohkubo, Shunichi Fukuzumi, Akira Sato, Mark ElsegoodMark Elsegood, Simon J. Teat, Katsuhiko ArigaPorphyrin derivatives bearing 2,6-di-tert-butylphenol
substituents at their 5,15-positions undergo reversible photoredox
switching between porphyrin and porphodimethene states as revealed
by UV vis spectroscopy, fluorescence spectroscopy, and X-ray singlecrystal
analyses. Photoredox interconversion is accompanied by substantial
variations in electronic absorption and fluorescence emission
spectra and a change of conformation of the tetrapyrrole macrocycle
from planar to roof-shaped. Oxidation proceeds only under photoillumination
of a dianionic state prepared through deprotonation using
fluoride anions. Conversely, photoreduction occurs in the presence of a sacrificial electron donor. Transient absorption
spectroscopy and electron spin resonance spectroscopy were applied to investigate the processes in photochemical reaction, and
radical intermediates were characterized. That is, photooxidation initially results in a phenol-substituent-centered radical, while the
reduction process occurs via a delocalized radical state involving both the macrocycle and 5,15-substituents. Forward and reverse
photochemical processes are governed by different chemical mechanisms, giving the important benefit that conversion reactions are
completely isolated, leading to better separation of the end states. Furthermore, energy diagrams based on electrochemical analyses
(cyclic voltammetry) were used to account for the processes occurring during the photochemical reactions. Our molecular design
indicates a simple and versatile method for producing photoredox macrocyclic compounds, which should lead to a new class of
advanced functional materials suitable for application in molecular devices and machines.
Funding
This research was partially supported by the World Premier International (WPI) Research Center Initiative on Materials Nanoarchitectonics and Grant-in-Aid (No. 20108010) from MEXT (Japan), Core Research for Evolutional Science and Technology (CREST) from JST (Japan), and KOSEF/MEST through the WCU project (R31-2008-000-10010-0). A.S. and J.L. are grateful to Japan Society for Promotion of Science (JSPS) for Fellowships. Advanced Light Source (ALS) is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02- 05CH11231.
History
School
- Science
Department
- Chemistry
Published in
JOURNAL OF THE AMERICAN CHEMICAL SOCIETYVolume
133Issue
40Pages
16119 - 16126 (8)Citation
ISHIHARA, S. ... et al., 2011. Reversible photoredox switching of porphyrin-pridged Bis-2,6-di-tert-butylphenols. Journal of the American Chemical Society, 133(40), pp.16119-16126.Publisher
© American Chemical SocietyVersion
- NA (Not Applicable or Unknown)
Publication date
2011Notes
This item is Closed Access.ISSN
0002-7863Publisher version
Language
- en