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Charge Separation in a Ruthenium-Quencher Conjugate Bound to DNA

Augustyn, Katherine E. and Stemp, E. D. A. and Barton, Jacqueline K. (2007) Charge Separation in a Ruthenium-Quencher Conjugate Bound to DNA. Inorganic Chemistry, 46 (22). pp. 9337-9350. ISSN 0020-1669. https://resolver.caltech.edu/CaltechAUTHORS:20160302-071129129

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Abstract

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.


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http://dx.doi.org/10.1021/ic701276tDOIArticle
http://pubs.acs.org/doi/abs/10.1021/ic701276tPublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/ic701276tPublisherSupporting Information
ORCID:
AuthorORCID
Stemp, E. D. A.0000-0003-2098-4214
Barton, Jacqueline K.0000-0001-9883-1600
Additional Information:© 2007 American Chemical Society. Received June 28, 2007. Publication Date (Web): October 2, 2007. We are grateful to the NIH for their financial support. We also thank M.C. DeRosa and E. Yavin for technical assistance.
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Issue or Number:22
Record Number:CaltechAUTHORS:20160302-071129129
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20160302-071129129
Official Citation:Charge Separation in a Ruthenium-Quencher Conjugate Bound to DNA Katherine E. Augustyn, E. D. A. Stemp, and Jacqueline K. Barton Inorganic Chemistry 2007 46 (22), 9337-9350 DOI: 10.1021/ic701276t
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64940
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:02 Mar 2016 17:12
Last Modified:09 Mar 2020 13:19

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