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ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 31, Number 5
BKCSDE 31(5)
May 20, 2010 |
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Title |
Comparison of the Binding Modes of [Ru(2,2'-bipyridine)3]2+ and
[Ru(2,2':6',2''-terpyridine)2]2+ to Native DNA
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Author |
Yoon Jung Jang, Hyun Mee Lee, Kyeung Joo Jang, Jae Cheol Lee, Seog K Kim, Tae Sub Cho* |
Keywords |
Ru(II) complex, Binding mode, DNA, Light Switch Effect, Polarized spectroscopy
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Abstract |
The [Ru(tpy)2]Cl2 (tpy:2,2':6',2"-terpyridine) complex was synthesized and its structure was confirmed by 1H-NMR and elemental analysis. Its binding mode toward DNA was compared with the well-known [Ru(bpy)3]Cl2 (bpy:2,2- bipyridyl), using isotropic absorption, linear dichroism(LD) spectroscopy, and an energy minimization study. Compared to [Ru (bpy)3]2+, the [Ru(tpy)2]2+ complex exhibited very little change in its absorption pattern, especially in the MLCT band, upon binding to DNA. Furthermore, upon DNA binding, both Ru(II) complexes induced a decrease in the LD magnitude in the DNA absorption region. The [Ru(tpy)2]2+ complex produced a strong positive LD signal in the ligand absorption region, which is in contrast with the [Ru(bpy)3]2+ complex. Observed spectral properties led to the conclusion that the interaction between the ligands and DNA bases is negligible for the [Ru(tpy)2]2+ complex, although it formed an adduct with DNA. This conclusion implies that both complexes bind to the surface of DNA, most likely to negatively charged phosphate groups via a simple electrostatic interaction, thereby orienting to exhibit the LD signal. The energy minimization calculation also supported this conclusion.
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1314 - 1318 |
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