Ultrafast IR spectroscopy of photo-induced electron transfer in self-assembled donor-acceptor coordination cages
2017 | journal article; research paper. A publication with affiliation to the University of Göttingen.
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Ultrafast IR spectroscopy of photo-induced electron transfer in self-assembled donor-acceptor coordination cages
Ahrens, J.; Frank, M.; Clever, G. H. & Schwarzer, D. (2017)
Physical Chemistry Chemical Physics, 19(21) pp. 13596-13603. DOI: https://doi.org/10.1039/c7cp02253k
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Details
- Authors
- Ahrens, J.; Frank, M.; Clever, Guido H.; Schwarzer, Dirk
- Abstract
- Photo-induced processes in self-assembled coordination cages were studied by femtosecond infrared pump-probe spectroscopy. Densely packed, interpenetrated double cages were constructed from eight bis-monodentate redoxactive ligands bound to four Pd(II) nodes. Two types of ligands consisting of electron rich phenothiazine (PTZ) or electron deficient anthraquinone (ANQ) chromophores were used to assemble either homo-octameric or mixed-ligand cages. Upon photoexcitation the homo-octameric acceptor cage undergoes intersystem crossing to a long-lived triplet state, similar to the free acceptor ligand. Excitation of the free donor ligand leads to a fluorescent state with intramolecular charge transfer character. This fluorescence is completely quenched in the homo-octameric donor double cage due to a ligand-to-metal charge transfer followed by back electron transfer on a ps timescale. Only for the mixed-ligand cage irradiation produces a charge separated state with an oxidized PTZ radical cation and a reduced ANQ radical anion as proven by their vibrational fingerprints in the transient IR spectra. In dichloromethane the lifetime of this charge separated state extends from tens of ps to >1.5 ns which is attributed to the broad distribution of mixed-ligand cages with different stoichiometry and/or stereo configurations.
- Issue Date
- 2017
- Journal
- Physical Chemistry Chemical Physics
- Project
- SFB 1073: Kontrolle von Energiewandlung auf atomaren Skalen
SFB 1073 | Topical Area B | B05 Energy conversion processes underlying the light-powered reversible guest exchange of photochromic coordination cages - ISSN
- 1463-9084; 1463-9076
- Sponsor
- Evonik Foundation; Deutsche Forschungsgemeinschaft [SFB 1073]