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Reversible photoredox switching of porphyrin-bridged bis-2,6-di- tert -butylphenols

Title
Reversible photoredox switching of porphyrin-bridged bis-2,6-di- tert -butylphenols
Authors
Ishihara S.Hill J.P.Shundo A.Richards G.J.Labuta J.Ohkubo K.Fukuzumi S.Sato A.Elsegood M.R.J.Teat S.J.Ariga K.
Ewha Authors
Shunichi Fukuzumi
SCOPUS Author ID
Shunichi Fukuzumiscopus
Issue Date
2011
Journal Title
Journal of the American Chemical Society
ISSN
0002-7863JCR Link
Citation
vol. 133, no. 40, pp. 16119 - 16126
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
Porphyrin 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 single-crystal 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. © 2011 American Chemical Society.
DOI
10.1021/ja2056165
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자연과학대학 > 화학·나노과학전공 > Journal papers
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