Charge Separation in a Ruthenium-Quencher Conjugate Bound to DNA
| Autor: | Eric D. A. Stemp, Katherine E. Augustyn, Jacqueline K. Barton |
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| Jazyk: | angličtina |
| Rok vydání: | 2007 |
| Předmět: |
Spectrometry
Mass Electrospray Ionization Quenching (fluorescence) Chemistry Guanine Radical Electron Spin Resonance Spectroscopy chemistry.chemical_element DNA Photochemistry Photoinduced electron transfer Ruthenium law.invention Inorganic Chemistry chemistry.chemical_compound Kinetics law Intramolecular force Spectrometry Mass Matrix-Assisted Laser Desorption-Ionization Physical and Theoretical Chemistry Electron paramagnetic resonance Acetonitrile |
| Popis: | A novel tris heteroleptic dipyridophenazine complex of ruthenium(II), [{Ru(phen)(dppz)(bpy‘-his)}{Ru(NH_3)_5}]^(5+), containing a covalently tethered ruthenium pentammine quencher coordinated through a bridging histidine has been synthesized and characterized spectroscopically and biochemically in a DNA environment and in organic solvent. Steady-state and time-resolved luminescence measurements indicate that the tethered Ru complex is quenched relative to the parent complexes [Ru(phen)(dppz)(bpy‘)]^(2+) and [Ru(phen)(dppz)(bpy‘-his)]^(2+) in DNA and acetonitrile, consistent with intramolecular photoinduced electron transfer. Intercalated into guanine-containing DNA, [{Ru(phen)(dppz)(bpy‘-his)}{Ru(NH_3)_5}]^(5+), upon excitation and intramolecular quenching, is capable of injecting charge into the duplex based upon the EPR detection of guanine radicals. DNA-mediated charge transport is also indicated using a kinetically fast cyclopropylamine-substituted base as an electron hole trap. Guanine damage is not observed, however, in measurements using the guanine radical as the kinetically slower hole trap, indicating that back electron-transfer reactions are competitive with guanine oxidation. Moreover, transient absorption measurements reveal a novel photophysical reaction pathway for [{Ru(phen)(dppz)(bpy‘-his)}{Ru(NH_3)_5}]^(5+) in the presence of DNA that is competitive with the intramolecular flash-quench process. These results illustrate the remarkably rich redox chemistry that can occur within a bimolecular ruthenium complex intercalated in duplex DNA. |
| Databáze: | OpenAIRE |
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