Ultrafast Excited-State Dynamics of DNA Fluorescent Intercalators: New Insight into the Fluorescence Enhancement Mechanism

Fürstenberg, Alexandre; Julliard, Marc D.; Deligeorgiev, Todor G.; Gadjev, Nikolai I.; Vasilev, Aleksey A.; Vauthey, Eric

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Title		Ultrafast Excited-State Dynamics of DNA Fluorescent Intercalators: New Insight into the Fluorescence Enhancement Mechanism
Authors		Fürstenberg, Alexandre Julliard, Marc D. Deligeorgiev, Todor G. Gadjev, Nikolai I. Vasilev, Aleksey A. Vauthey, Eric
Published in		Journal of the American Chemical Society. 2006, vol. 128, no. 23, p. 7661-7669
Abstract		The excited-state dynamics of the DNA bisintercalator YOYO-1 and of two derivatives has been investigated using ultrafast fluorescence up-conversion and time-correlated single photon counting. The free dyes in water exist in two forms: nonaggregated dyes and intramolecular H-type aggregates, the latter form being only very weakly fluorescent because of excitonic interaction. The excited-state dynamics of the nonaggregated dyes is dominated by a nonradiative decay with a time constant of the order of 5 ps associated with large amplitude motion around the monomethine bridge of the cyanine chromophores. The strong fluorescence enhancement observed upon binding of the dyes to DNA is due to both the inhibition of this nonradiative deactivation of the nonaggregated dyes and the dissociation of the aggregates and thus to the disruption of the excitonic interaction. However, the interaction between the two chromophoric moieties in DNA is sufficient to enable ultrafast hopping of the excitation energy as revealed by the decay of the fluorescence anisotropy. Finally, these dyes act as solvation probes since a dynamic fluorescence Stokes shift was observed both in bulk water and in DNA. Very similar time scales were found in bulk water and in DNA.
Identifiers		DOI: 10.1021/ja0609001
Full text		Article (Published version) - Free access Other version: http://pubs.acs.org/cgi-bin/article.cgi/jacsat/2006/128/i23/pdf/ja0609001.pdf
Structures		Faculté des sciences / Section de chimie et biochimie / Département de chimie physique
Research group		Groupe Vauthey
Citation (ISO format)		FÜRSTENBERG, Alexandre et al. Ultrafast Excited-State Dynamics of DNA Fluorescent Intercalators: New Insight into the Fluorescence Enhancement Mechanism. In: Journal of the American Chemical Society, 2006, vol. 128, n° 23, p. 7661-7669. https://archive-ouverte.unige.ch/unige:3648