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Belt-Shaped π-Syste...
Belt-Shaped π-Systems: Relating Geometry to Electronic Structure in a Six-Porphyrin Nanoring
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- Sprafke, Johannes K. (author)
- University Of Oxford
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- Kondratuk, Dmitry V. (author)
- University Of Oxford
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- Wykes, Michael (author)
- Universite de Mons
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- Thompson, Amber L. (author)
- University Of Oxford
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- Hoffmann, Markus (author)
- University Of Oxford
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- Drevinskas, Rokas (author)
- Lund University,Lunds universitet,Kemisk fysik,Enheten för fysikalisk och teoretisk kemi,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Chemical Physics,Physical and theoretical chemistry,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH
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- Chen, Wei-Hsin (author)
- University Of Oxford
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- Yong, Chaw Keong (author)
- University Of Oxford
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- Kärnbratt, Joakim, 1982 (author)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Bullock, Joseph E. (author)
- Northwestern University
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- Malfois, Marc (author)
- Diamond Light Source
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- Wasielewski, Michael R. (author)
- Northwestern University
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- Albinsson, Bo, 1963 (author)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Herz, Laura M. (author)
- University Of Oxford
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- Zigmantas, Donatas (author)
- Lund University,Lunds universitet,Kemisk fysik,Enheten för fysikalisk och teoretisk kemi,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Chemical Physics,Physical and theoretical chemistry,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH
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- Beljonne, David (author)
- Universite de Mons
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- Anderson, Harry L. (author)
- University Of Oxford
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(creator_code:org_t)
- 2011-10-12
- 2011
- English.
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In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 133:43, s. 17262-17273
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Abstract
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- Linear pi-conjugated oligomers have been widely investigated, but the behavior of the corresponding cyclic oligomers is poorly understood, despite the recent synthesis of pi-conjugated macrocycles such as [n]cycloparaphenylenes and cyclo[n]thiophenes. Here we present an efficient template-directed synthesis of a pi-conjugated butadiyne-linked cyclic porphyrin hexamer directly from the monomer. Small-angle X-ray scattering data show that this nanoring is shape-persistent in solution, even without its template, whereas the linear porphyrin hexamer is relatively flexible. The crystal structure of the nanoring-template complex shows that most of the strain is localized in the acetylenes; the porphyrin units are slightly curved, but the zinc coordination sphere is undistorted. The electrochemistry, absorption, and fluorescence spectra indicate that the HOMO-LUMO gap of the nanoring is less than that of the linear hexamer and less than that of the corresponding polymer. The nanoring exhibits six one-electron reductions and six one-electron oxidations, most of which are well resolved. Ultrafast fluorescence anisotropy measurements show that absorption of light generates an excited state that is delocalized over the whole pi-system within a time of less than 0.5 ps. The fluorescence spectrum is amazingly structured and red-shifted. A similar, but less dramatic, red-shift has been reported in the fluorescence spectra of cycloparaphenylenes and was attributed to a high exciton binding energy; however the exciton binding energy of the porphyrin nanoring is similar to those of linear oligomers. Quantum-chemical excited state calculations show that the fluorescence spectrum of the nanoring can be fully explained in terms of vibronic Herzberg-Teller (HT) intensity borrowing.
Subject headings
- NATURVETENSKAP -- Kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences (hsv//eng)
- NATURVETENSKAP -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)
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- art (subject category)
- ref (subject category)
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Sprafke, Johanne ...
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Kondratuk, Dmitr ...
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Wykes, Michael
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Thompson, Amber ...
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Hoffmann, Markus
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Drevinskas, Roka ...
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Chen, Wei-Hsin
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Yong, Chaw Keong
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Kärnbratt, Joaki ...
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Bullock, Joseph ...
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Malfois, Marc
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Wasielewski, Mic ...
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Albinsson, Bo, 1 ...
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Herz, Laura M.
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Zigmantas, Donat ...
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Beljonne, David
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Anderson, Harry ...
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Chemical Science ...
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NATURAL SCIENCES
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and Physical Science ...
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and Atom and Molecul ...
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Chalmers University of Technology
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Lund University