Iridium(III)-based minor groove binding complexes as DNA photocleavage agents

Stephen O Aderinto, Torsten John, Abdulmujeeb Onawole, Raphael Peter Galleh, Jim A Thomas

Research output: Contribution to journalArticlepeer-review


Transition metal complexes containing the qtpy ligand (2':4,4'':4',4'''-quaterpyridyl) are known to be DNA intercalators or minor groove binders. In this study, new tricationic iridium(III) complexes of qtpy are reported. Both [Ir(bpy) 2(qtpy)] 3+1 and [Ir(phen) 2(qtpy)] 3+2 display good water solubility as chloride salts. The complexes possess high-energy excited states, which are quenched in the presence of duplex DNA and even by the mononucleotides guanosine monophosphate and adenosine monophosphate. Further studies reveal that although the complexes bind to quadruplex DNA, they display a preference for duplex structures, which are bound with an order of magnitude higher affinities than their isostructural dicationic Ru II-analogues. Detailed molecular dynamics simulations confirm that the complexes are groove binders through the insertion of, predominantly, the qtpy ligand into the minor groove. Photoirradiation of 1 in the presence of plasmid DNA confirms that this class of complexes can function as synthetic photonucleases by cleaving DNA.

Original languageEnglish
Pages (from-to)7282-7291
Number of pages10
JournalDalton Transactions
Issue number17
Publication statusPublished - 30 Apr 2024

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This article is licensed under aCreative Commons Attribution-NonCommercial 3.0 Unported Licence.

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© 2024 The Royal Society of Chemistry.


  • Iridium/chemistry
  • DNA/chemistry
  • Coordination Complexes/chemistry
  • DNA Cleavage
  • Molecular Dynamics Simulation
  • Ligands
  • Molecular Structure


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