دورية أكاديمية
Belt-shaped π-systems: relating geometry to electronic structure in a six-porphyrin nanoring.
| العنوان: | Belt-shaped π-systems: relating geometry to electronic structure in a six-porphyrin nanoring. |
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| المؤلفون: | Sprafke JK; Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford OX1 3TA, United Kingdom., Kondratuk DV, Wykes M, Thompson AL, Hoffmann M, Drevinskas R, Chen WH, Yong CK, Kärnbratt J, Bullock JE, Malfois M, Wasielewski MR, Albinsson B, Herz LM, Zigmantas D, Beljonne D, Anderson HL |
| المصدر: | Journal of the American Chemical Society [J Am Chem Soc] 2011 Nov 02; Vol. 133 (43), pp. 17262-73. Date of Electronic Publication: 2011 Oct 12. |
| نوع المنشور: | Journal Article; Research Support, Non-U.S. Gov't |
| اللغة: | English |
| بيانات الدورية: | Publisher: American Chemical Society Country of Publication: United States NLM ID: 7503056 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1520-5126 (Electronic) Linking ISSN: 00027863 NLM ISO Abbreviation: J Am Chem Soc Subsets: MEDLINE |
| أسماء مطبوعة: | Publication: Washington, DC : American Chemical Society Original Publication: Easton, Pa. [etc.] |
| مواضيع طبية MeSH: | Nanostructures/*chemistry , Porphyrins/*chemistry, Electrons ; Models, Molecular ; Molecular Structure ; Organometallic Compounds/chemical synthesis ; Organometallic Compounds/chemistry ; Porphyrins/chemical synthesis |
| مستخلص: | Linear π-conjugated oligomers have been widely investigated, but the behavior of the corresponding cyclic oligomers is poorly understood, despite the recent synthesis of π-conjugated macrocycles such as [n]cycloparaphenylenes and cyclo[n]thiophenes. Here we present an efficient template-directed synthesis of a π-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 π-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. |
| المشرفين على المادة: | 0 (Organometallic Compounds) 0 (Porphyrins) |
| تواريخ الأحداث: | Date Created: 20110924 Date Completed: 20120213 Latest Revision: 20111026 |
| رمز التحديث: | 20240628 |
| DOI: | 10.1021/ja2045919 |
| PMID: | 21939246 |
| قاعدة البيانات: | MEDLINE |
Find this issue from the American Chemical Society | تدمد: | 1520-5126 |
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| DOI: | 10.1021/ja2045919 |