Photooxidation of guanine by a ruthenium dipyridophenazine complex intercalated in a double-stranded polynucleotide monitored directly by picosecond visible and infrared transient absorption spectroscopy

Benjamin Elias, Caitriona Creely, Gerard W. Doorley, Martin M. Feeney, Cécile Moucheron, Andrée Kirsch-DeMesmaeker, Joanne Dyer, David Grills, Michael W. George, Pavel Matousek, Anthony W. Parker, Michael Towrie, John M. Kelly

Research output: Contribution to journalArticle

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Abstract

Transient species formed by photoexcitation (400 nm) of [Ru(dppz)(tap) 2]2+ (1) (dppz = dipyrido[3,2-a:2′,3′-c] phenazine; tap= 1,4,5,8-tetraazaphenanthrene) in aqueous solution and when intercalated into a double-stranded synthetic polynucleotide, [poly(dG-dC)] 2, have been observed on a picosecond timescale by both visible transient absorption (allowing monitoring of the metal complex intermediates) and transient infrared (IR) absorption spectroscopy (allowing direct study of the DNA nucleobases). By contrast with its behavior when free in aqueous solution, excitation of 1 when bound to [poly(dG-dC)]2 causes a strong increase in absorbance at 515 nm due to formation of the reduced complex [Ru(dppz)-(tap)2]+ (rate constant = (2.0 ± 0.2) × 109 s-1). The subsequent reformation of 1 proceeds with a rate constant of (1.1 ± 0.2) × 108 s -1. When the process is carried out in D2O. the rates of formation and removal of [Ru(dppz)(tap)2] + are reduced (rate constants (1.5 ± 0.3) × 109and (0.7±0.2) × 108 s-1 respectively) consistent with proton-coupled electron transfer processes. Picosecond transient IR measurements in the 1540-1720 cm-1 region in D2O solution confirm that the reduction of 1 intercalated into [poly(dG-dC)]2 is accompanied by bleaching of IR ground-state bands of guanine (1690 cm-1) and cytosine (1656 cm-1), each with similar rate constants.

Original languageEnglish
Pages (from-to)369-375
Number of pages7
JournalChemistry - A European Journal
Volume14
Issue number1
DOIs
Publication statusPublished - 2008

Fingerprint

Polynucleotides
Photooxidation
Guanine
Ruthenium
Absorption spectroscopy
Rate constants
Infrared radiation
Photoexcitation
Cytosine
Coordination Complexes
Infrared absorption
Bleaching
Metal complexes
Ground state
Protons
Infrared spectroscopy
DNA
ruthenium dipyridophenazine
Electrons
Monitoring

Keywords

  • Electron transfer
  • Guanine
  • Photooxidation
  • Reaction mechanisms
  • Ruthenium

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Photooxidation of guanine by a ruthenium dipyridophenazine complex intercalated in a double-stranded polynucleotide monitored directly by picosecond visible and infrared transient absorption spectroscopy. / Elias, Benjamin; Creely, Caitriona; Doorley, Gerard W.; Feeney, Martin M.; Moucheron, Cécile; Kirsch-DeMesmaeker, Andrée; Dyer, Joanne; Grills, David; George, Michael W.; Matousek, Pavel; Parker, Anthony W.; Towrie, Michael; Kelly, John M.

In: Chemistry - A European Journal, Vol. 14, No. 1, 2008, p. 369-375.

Research output: Contribution to journalArticle

Elias, B, Creely, C, Doorley, GW, Feeney, MM, Moucheron, C, Kirsch-DeMesmaeker, A, Dyer, J, Grills, D, George, MW, Matousek, P, Parker, AW, Towrie, M & Kelly, JM 2008, 'Photooxidation of guanine by a ruthenium dipyridophenazine complex intercalated in a double-stranded polynucleotide monitored directly by picosecond visible and infrared transient absorption spectroscopy', Chemistry - A European Journal, vol. 14, no. 1, pp. 369-375. https://doi.org/10.1002/chem.200700564
Elias, Benjamin ; Creely, Caitriona ; Doorley, Gerard W. ; Feeney, Martin M. ; Moucheron, Cécile ; Kirsch-DeMesmaeker, Andrée ; Dyer, Joanne ; Grills, David ; George, Michael W. ; Matousek, Pavel ; Parker, Anthony W. ; Towrie, Michael ; Kelly, John M. / Photooxidation of guanine by a ruthenium dipyridophenazine complex intercalated in a double-stranded polynucleotide monitored directly by picosecond visible and infrared transient absorption spectroscopy. In: Chemistry - A European Journal. 2008 ; Vol. 14, No. 1. pp. 369-375.
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