| Autor: |
Kaletaş BK; Molecular Photonic Materials, van't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Nieuwe Achtergracht 166, 1018 WS Amsterdam, The Netherlands., Mandl C, van der Zwan G, Fanti M, Zerbetto F, De Cola L, König B, Williams RM |
| Jazyk: |
angličtina |
| Zdroj: |
The journal of physical chemistry. A [J Phys Chem A] 2005 Jul 28; Vol. 109 (29), pp. 6440-9. |
| DOI: |
10.1021/jp051035u |
| Abstrakt: |
Arcyriarubin A and arcyriaflavin A, two strongly emissive and intensely colored natural products containing both two indoles and a maleimide unit, are investigated (in the flavin the two indole moieties are coupled by a cyclization). The photophysical properties of these compounds were studied in several solvents using UV-vis absorption, steady-state and time-resolved emission, nano- and femtosecond transient absorption spectroscopy. Furthermore, the effect of complexation with zinc(II) 1,4,7,11-tetraazacyclododecane on the photophysical properties of these natural products has been investigated. The chemical structures of the compounds would suggest a charge transfer (CT) character in the ground and/or excited states, since indole is a well-known electron donor and maleimide is a good electron acceptor. Their solvatochromic behavior was investigated by using the Kamlet-Taft approach and indicates only a small CT character in the excited state. This is substantiated by the time-resolved spectroscopy and the complexation study. Molecular orbital calculations indicate that there are no electronic transitions in which a large electron density is transferred from one indole unit to the maleimide part. All calculated orbitals show a strong delocalization of the electron density over the whole molecule. These findings corroborate the experimental results. Whereas the two compounds do have a substantial (calculated) ground-state dipole moment (6 D) and show some solvatochromic behavior, they behave more like conjugated aromatic systems than like electron donor-acceptor systems. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
|
