Merz, Thomas and Wenninger, Matthias and Weinberger, Michael and Riedle, Eberhard and Wagenknecht, Hans-Achim and Schuetz, Martin (2013) Conformational control of benzophenone-sensitized charge transfer in dinucleotides. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 15 (42). pp. 18607-18619. ISSN 1463-9076, 1463-9084
Full text not available from this repository. (Request a copy)Abstract
Charge transfer in DNA cannot be understood without addressing the complex conformational flexibility, which occurs on a wide range of timescales. In order to reduce this complexity four dinucleotide models 1X consisting of benzophenone linked by a phosphodiester to one of the natural nucleosides X = A, G, T, C were studied in water and methanol. The theoretical work focuses on the dynamics and electronic structure of 1G. Predominant conformations in the two solvents were obtained by molecular dynamics simulations. 1G in MeOH adopts mainly an open geometry with a distance of 12-16 angstrom between the two aromatic parts. In H2O the two parts of 1G form primarily a stacked conformation yielding a distance of 5-6 angstrom. The low-lying excited states were investigated by electronic structure theory in a QM/MM environment for representative snapshots of the trajectories. Photo-induced intramolecular charge transfer in the S-1 state occurs exclusively in the stacked conformation. Ultrafast transient absorption spectroscopy with 1X reveals fast charge transfer from S-1 in both solvents with varying yields. Significant charge transfer from the T-1 state is only found for the nucleobases with the lowest oxidation potential: in H2O, charge transfer occurs with 3.2 x 10(9) s(-1) for 1A and 6.0 x 10(9) s(-1) for 1G. The reorganization energy remains nearly unchanged going from MeOH to the more polar H2O. The electronic coupling is rather low even for the stacked conformation with H-AB = 3 meV and explains the moderate charge transfer rates. The solvent controls the conformational distribution and therefore gates the charge transfer due to differences in distance and stacking.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | THE-IDENTITY APPROXIMATION; DENSITY-FUNCTIONAL THEORY; GAUSSIAN-BASIS SETS; ELECTRON-TRANSFER; DNA HAIRPINS; MODEL CC2; RIBONUCLEOTIDE REDUCTASES; TRANSFER DYNAMICS; REDOX POTENTIALS; RESOLUTION; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Research Group Theoretical Chemistry > Prof. Dr. Martin Schütz |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 29 Apr 2020 04:42 |
| Last Modified: | 29 Apr 2020 04:42 |
| URI: | https://pred.uni-regensburg.de/id/eprint/17359 |
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