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DNA Sequence and Ancillary Ligand Modulate the Biexponential Emission Decay of Intercalated [Ru(L)2dppz]2+ Enantiomers

A. McKinley ; Johanna Andersson (Institutionen för kemi- och bioteknik, Fysikalisk kemi) ; Per Lincoln (Institutionen för kemi- och bioteknik, Fysikalisk kemi) ; E. M. Tuite
Chemistry - A European Journal (0947-6539). Vol. 18 (2012), 47, p. 15142-15150.
[Artikel, refereegranskad vetenskaplig]

The bi-exponential emission decay of [Ru(L)2dppz]2+ (L=N,N'-diimine ligand) bound to DNA has been studied as a function of polynucleotide sequence, enantiomer, and nature of L (phenanthroline vs. bipyridine). The lifetimes (ti) and pre-exponential factors (ai) depend on all three parameters. With [poly(dA-dT)]2, the variation of ai with [Nu]/[Ru] has little dependence on L for ?-[Ru(L)2dppz]2+ but a substantial dependence for ?-[Ru(L)2dppz]2+. With [poly(dG-dC)]2, by contrast, the ?-enantiomer ai values depend strongly on the nature of L, whereas those of the ?-enantiomer are relatively unaffected. DNA-bound linked dimers show similar photophysical behaviour. The lifetimes are identified with two geometries of minor-groove intercalated [Ru(L)2dppz]2+, resulting in differential water access to the phenazine nitrogen atoms. Interplay of cooperative and anti-cooperative binding resulting from complexcomplex and complexDNA interactions is responsible for the observed variations of ai with binding ratio. [Ru(phen)2dppz]2+ emission is quenched by guanosine in DMF, which may further rationalise the shorter lifetimes observed with guanine-rich DNA.

Nyckelord: DNA, intercalation, luminescence lifetimes, photochemistry, ruthenium, light-switch mechanism, metal-complexes, dipyridophenazine complexes, electron-transfer, minor-groove, ruthenium(ii), binding, temperature, spectroscopy

Denna post skapades 2013-01-18.
CPL Pubid: 171443


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Institutionen för kemi- och bioteknik, Fysikalisk kemi (2005-2014)



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