Intercalation of bulky Δ,Δ- and Λ,Λ-bis-Ru(II) complex between DNA base pairs

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4+ complexes, which suggested that the bridging moiety sits in the minor groove of the polynucleotide. As luminescence intensity increased, decay times became longer and complexes were wellprotected from the negatively charged iodide quencher compared to that in the absence of poly[d(A-T) 2 ]. These luminescence measurements indicated that Ru(II) enantiomers were in a less polar environment compared to that in water and supported by minor groove binding. An angle of 45° between the molecular plane of the bridging moiety of the ΔΔ-[μ-Ru 2 (phen) 4 (bip)]4+ complex and the local DNA helix axis calculated from reduced linear dichroism (LD 4+ are able to discriminate between AT and GC base pairs.

Section: -40mentioning

confidence: 99%

Sequence Dependent Binding Modes of the ΔΔ- and ΛΛ-binuclear Ru(II) Complexes to poly[d(G-C)₂] and poly[d(A-T)₂]

Chitrapriya¹,

Kim²,

Jang³

et al. 2013

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“…When bound to DNA, one of the Ru(II) locates in the minor groove of the DNA, while the other in the major groove. 23 In contrast, when the two dppz moieties were connected by a flexi-1616 Bull. Korean Chem.…”

Section: +mentioning

confidence: 99%

“…Measurement of normal absorption spectra and linear dichroism (LD) spectra has been described elsewhere. 23 The reduced LD (LD r ), defined by the ratio of measured LD to the isotropic absorption spectrum, [25][26][27] and related to the angle between the DNA helical axis and electronic transition moment of the DNA-bound Ru(II) complexes, was analyzed based on a detailed discussion for the electronic transition moment of the [Ru(phen) 2 …”

Section: Synthesis Of the [µ-(B)(pf6)2(dppz)2(phen)2ru2]mentioning

confidence: 99%

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Binding Modes of New Bis-Ru(II) Complexes to DNA: Effect of the Length of the Linker

Kwon¹,

Choi²,

Lee³

et al. 2010

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Bis-[dipyrido[3,2-a:2',3'-c]phenazine)2(1,10-phenanthroline)2Ru2] 2+ complexes (bis-Ru(II) complexes) tethered by linkers of various lengths were synthesized and their binding properties to DNA investigated by normal absorption and linear dichroism spectra, and fluorescence techniques in this study. Upon binding to DNA, the bis-Ru(II) complex with the longest linker (1,3-bis-(4-pyridyl)-propane), exhibited a negative LD r signal whose intensity was as large as that in the DNA absorption region, followed by a complicate LD r signal in the metal-to-ligand charge transfer region. The luminescence intensity of this bis-Ru(II) complex was enhanced. The observed LD r and luminescence results resembled that of the [Ru(1,10-phenanthroline)2dipyrido[3,2-a:2',3'-c]phenazine] 2+ complex, whose dipyrido[3,2-a:2',3'-c]phenazine (dppz) ligand has been known to intercalate between DNA bases. Hence, it is conclusive that both dppz ligands of the bis-Ru(II) complex intercalate. The binding stoichiometry, however, was a single intercalated dppz per ~ 2.3 bases, which violates the "nearest binding site exclusion" model for intercalation. The length between the two Ru(II) complexes may be barely long enough to accommodate one DNA base between the two dppz ligands, but not for two DNA bases. When the linker was shorter (4,4'-bipyridine or 1,2-bis-(4-pyridyl)-ethane), the magnitude of the LD in the dppz absorption region, as well as the luminescence intensity of both bis-Ru(II) complexes, was half that of the bis-Ru(II) complex bearing a long linker. This observation can be elucidated by a model whereby one of the dppz ligands intercalates while the other is exposed to the aqueous environment.

“…17 The ratio of measured LD to the isotropic absorption spectrum resulted in a wavelength-dependent quantity called the reduced LD (LD r ) 18-20 which is related to the angle between the DNA helical axis and the electronic transition moment of the DNA-bound Ru(II) complexes. The intensity of LD depends on the orientation factor and optical factor.…”

Section: Linear Dichroism (Ld)mentioning

confidence: 99%

Comparison of Binding Stoichiometry of [Ru(1,10-phenanthroline)₂dipyrido [3,2-a:2',3'-c]phenazine]²⁺and its Bis-derivative to DNA

Jang

Lee²,

Lee³

2010

A new bis-Ru(II) complex, in which two [Ru(1,10-phenanthroline)2dipyrido[3,2-a:2',3'-c]phenazine] 2+ were tethered by a 1,3-bis(4-pyridyl)propane linker, was synthesized and its binding mode and stoichiometry to DNA was investigated by optical spectroscopy including linear dichroism (LD) and fluorescence intensity measurement. The magnitude of the negatively reduced LD signal of the bis-Ru(II) complex in the dipyrido[3,2-a:2',3'-c]phenazine (DPPZ) ligand absorption region appeared to be similar compared to that in the DNA absorption region, which is considered to be a diagnostic for DPPZ ligand intercalation. The binding stoichiometry measured from its LD magnitude and enhanced fluorescence intensity corresponds to one ligand per three DNA bases, effectively violating the nearest neighbouring site exclusion model for classical DNA intercalation. This observation is in contrast with monomer analogue [Ru(1,, which is saturated at the DPPZ ligand to DNA base ratio of 0.25, or one DPPZ ligand per four nucleobases.