Binding Geometry and Photophysical Properties of DNA-Threading Binuclear Ruthenium
Complexes
Fredrik Westerlund
Mattias P. Eng
Mikael U. Winters
Per Lincoln
10.1021/jp065871v.s001
https://acs.figshare.com/articles/journal_contribution/Binding_Geometry_and_Photophysical_Properties_of_DNA_Threading_Binuclear_Ruthenium_Complexes/3033514
The DNA binding conformation and the photophysical properties of the semiflexible binuclear ruthenium
complex [μ-bidppz(phen)<sub>4</sub>Ru<sub>2</sub>]<sup>4+</sup> (<b>2</b>) were studied with optical spectroscopy and compared to the rigid, planar
homologue in syn conformation [μ-dtpf(phen)<sub>4</sub>Ru<sub>2</sub>]<sup>4+</sup> (<b>3</b>) and the parent “light-switch” complex [Ru(phen)<sub>2</sub>dppz]<sup>2+</sup> (<b>1</b>). Comparison of calculated and observed absorption bands of the bridging ligand, bidppz,
confirm earlier suggestions that <b>2</b> is significantly nonplanar, both free in solution and when intercalated into
poly(dAdT)<sub>2</sub>, but the conclusion that the intercalated conformation is an anti rotamer is not substantiated by
comparison of linear and circular dichroism spectra of <b>2</b> and <b>3</b>. The behavior of the emission quantum yield
as a function of temperature is similar for the two binuclear complexes <b>2</b> and <b>3</b> in different protic solvents,
and a quantitative analysis suggests that, in solution, the solvent is more strongly hydrogen bonded to the
excited state of <b>2</b> than to <b>1</b>. However, the observation that for <b>2</b> the radiative rate constant increases to a
value similar to <b>1</b> upon intercalation into DNA suggests that the difference between <b>1</b> and <b>2</b> in accepting
hydrogen bonds is less pronounced when intercalated.
2007-01-11 00:00:00
intercalated conformation
solution
photophysical properties
complexes 2
Binding Geometry
protic solvents
bidppz
Photophysical Properties
dichroism spectra
DNA
radiative rate
emission quantum
hydrogen bonds
absorption bands