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

Lookup NU author(s): Andrew McKinley, Dr Eimer TuiteORCiD

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Abstract

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.

Publication metadata

Author(s): McKinley AW, Andersson J, Lincoln P, Tuite EM

Publication type: Article

Publication status: Published

Journal: Chemistry: A European Journal

Year: 2012

Volume: 18

Issue: 47

Pages: 15142 – 15150

Print publication date: 19/11/2012

ISSN (print): 0947-6539

ISSN (electronic): 1521-3765

Publisher: Wiley - V C H Verlag GmbH & Co. KGaA

URL: http://dx.doi.org/10.1002/chem.201201279

DOI: 10.1002/chem.201201279

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