title: Trapped in imidazole: how to accumulate multiple photoelectrons on a black-absorbing ruthenium complex.
abstract: Ruthenium dyes incorporating a 4H-imidazole chromophore as a ligand exhibit a spectrally broad absorption in the UV/Vis region. Furthermore, they show the ability to store two electrons within the 4H-imidazole ligand. These features render them promising molecular systems, for example, as inter- or intramolecular electron relays. To optimize the structures with respect to their electron-storage capability, it is crucial to understand the impact of structural changes accompanying photoinduced charge transfer in the electronic intermediates of multistep electron-transfer processes. The photophysical properties of these (reactive) intermediates might impact the function of the molecular systems quite substantially. However, the spectroscopic study of short-lived intermediates in stepwise multielectron-transfer processes is experimentally challenging. To this end, this contribution reports on the electrochemical generation of anions identical to intermediate structures and their spectroscopic characterization by in situ resonance Raman and UV/Vis spectroelectrochemistry and computational methods. Thereby, an efficient two-electron pathway to the 4H-imidazole electron-accepting ligand is identified.
authors.affiliation: Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena (Germany), Fax: (+49) 3641-948302.
authors.forename: Linda
authors.initials: L
authors.lastname: Zedler
authors.forename: Stephan
authors.initials: S
authors.lastname: Kupfer
authors.forename: Inês Rabelo
authors.initials: IR
authors.lastname: de Moraes
authors.forename: Maria
authors.initials: M
authors.lastname: Wächtler
authors.forename: Rainer
authors.initials: R
authors.lastname: Beckert
authors.forename: Michael
authors.initials: M
authors.lastname: Schmitt
authors.forename: Jürgen
authors.initials: J
authors.lastname: Popp
authors.forename: Sven
authors.initials: S
authors.lastname: Rau
authors.forename: Benjamin
authors.initials: B
authors.lastname: Dietzek
keywords: Raman spectroscopy; TD DFT calculations; electron transfer; ruthenium; spectroelectrochemistry