title: Photophysics of Ru(II) Dyads Derived from Pyrenyl-Substitued Imidazo[4,5-f][1,10]phenanthroline Ligands.
abstract: The photophysics of a series of Ru(II) dyads based on the 2-(1-pyrenyl)-1H-imidazo[4,5-f][1,10]-phenanthroline ligand was investigated. The ability of these metal complexes to intercalate DNA and induce cell death upon photoactivation makes them attractive photosensitizers for a range of photobiological applications, including photodynamic therapy. In the present study, time-resolved transient absorption and emission spectroscopy were used to interrogate the photoinduced processes that follow metal-to-ligand charge transfer excitation of the complexes in solution. It was found that energy transfer to pyrene-localized intraligand triplet states, facilitated by torsional motion of the pyrene moiety relative to the imidazo[4,5-f][1,10]phenanthroline ligand, was an important relaxation pathway governing the photophysical dynamics in this class of compounds. Biphasic decay kinetics were assigned to spontaneous (pre-equilibrium) and delayed emission, arising from an equilibrium established between (3)MLCT and (3)IL states. TDDFT calculations supported these interpretations.
authors.affiliation: †Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller-University Jena, Helmholtzweg 4, 07743 Jena, Germany.|‡Leibniz Institute of Photonic Technology (IPHT) e.V., Albert-Einstein-Straße 9, 07745 Jena, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Reichardt
authors.affiliation: §Department of Chemistry, Acadia University, Wolfville, NS B4P 2R6, Canada.
authors.forename: Mitch
authors.initials: M
authors.lastname: Pinto
authors.affiliation: ‡Leibniz Institute of Photonic Technology (IPHT) e.V., Albert-Einstein-Straße 9, 07745 Jena, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Wächtler
authors.affiliation: §Department of Chemistry, Acadia University, Wolfville, NS B4P 2R6, Canada.
authors.forename: Mat
authors.initials: M
authors.lastname: Stephenson
authors.affiliation: †Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller-University Jena, Helmholtzweg 4, 07743 Jena, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Kupfer
authors.affiliation: §Department of Chemistry, Acadia University, Wolfville, NS B4P 2R6, Canada.
authors.forename: Tariq
authors.initials: T
authors.lastname: Sainuddin
authors.affiliation: ∥Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland.
authors.forename: Julien
authors.initials: J
authors.lastname: Guthmuller
authors.affiliation: §Department of Chemistry, Acadia University, Wolfville, NS B4P 2R6, Canada.
authors.forename: Sherri A
authors.initials: SA
authors.lastname: McFarland
authors.affiliation: †Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller-University Jena, Helmholtzweg 4, 07743 Jena, Germany.|‡Leibniz Institute of Photonic Technology (IPHT) e.V., Albert-Einstein-Straße 9, 07745 Jena, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Dietzek