[Ru(phen)2DPPZ]2+ is in contact with DNA bases when it forms a luminescent complex with single-stranded oligonucleotides

Seok Joon Moon, Jong Moon Kim, Ji Youn Choi, Seog K. Kim, Je Seung Lee, Ho G. Jang

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)


The luminescence intensity of the Δ- and Λ-enantiomer of [Ru(phen)2DPPZ]2+ ([Ru(phenanthroline)2 dipyrido[3,2-a:2′,3′-c]phenazine]2+) complex enhanced upon binding to double stranded DNA, which has been known as "light switch effect". The enhancement of the luminescence required the intercalation of the large ligand between DNA base pairs. In this study, we report the enhancement in the luminescence intensity when the metal complexes bind to single stranded oligonucleotides, indicating that the "light switch effect" does not require intercalation of the large DPPZ ligand. Oligonucleotides may provide a hydrophobic cavity for the [Ru(phen) 2DPPZ]2+ complex to prevent the quenching by the water molecule. In the cavity, the metal complex is in contact with DNA bases as is evidenced by the observation that the excited energy of the DNA bases transfer to the bound metal complex. However, the contact of the metal complex with DNA bases is different from the stacking of DPPZ in the intercalation pocket. In addition to the normal two luminescence lifetimes, a short lifetime in the range of 1-2 ns was found for both the Δ- and Λ-enantiomer of [Ru(phen)2DPPZ]2+ when complexed with single stranded oligonucleotides, which may be assigned to the metal complex that is outside of the cavity, interacting with phosphate groups of DNA.

Original languageEnglish
Pages (from-to)994-1000
Number of pages7
JournalJournal of Inorganic Biochemistry
Issue number5
Publication statusPublished - 2005 May

Bibliographical note

Funding Information:
This work was supported by Korea Research Foundation (Grant No. KRF 2002-070-C00053).


  • Contact energy transfer
  • DNA
  • Light switch
  • [Ru(phen)DPPZ]

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry


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