title: Elaboration of covalently linked polyoxometalates with ruthenium and pyrene chromophores and characteriation of their photophysical properties.
abstract: Keggin and Dawson-type polyoxometalates (POMs) decorated by organometallic [cyclometalated ruthenium(II) polypyridine complex] or organic (pyrene) chromophores were prepared by postfunctionalization of hybrid disilylated POM platforms. The connection is made in a very efficient and modular way via Sonogashira coupling reactions, which provide a rigid linkage between the POM and the photoactive centers. Electronic properties have been inferred from electrochemical and photophysical studies and reflect poor electronic interactions between both partners. The presence of the POM leads to luminescence quenching of the chromophores, which was attributed to an intramolecular electron transfer from the chromophore to the POM. The rate of this process is much faster in the POM-pyrene than in the POM-Ru system. It depends on the driving force dictated by the redox potentials of both partners but also in the case of the POM-Ru system on the presence of the metallacycle, which acts as a molecular insulator and delays the intramolecular electron transfer. In the POM-Ru system, a comparative study of the luminescence quenching showed that the electron transfer is still more important in the covalently bonded hybrids than in systems where the POM and the ruthenium complexes are assembled via electrostatic interactions.
authors.affiliation: Institut Parisien de Chimie Moléculaire, UMR CNRS 7201, UPMC Université Paris 06, 4 place Jussieu, 75252 Paris cedex 05, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Matt
authors.forename: Christophe
authors.initials: C
authors.lastname: Coudret
authors.forename: Christine
authors.initials: C
authors.lastname: Viala
authors.forename: Damien
authors.initials: D
authors.lastname: Jouvenot
authors.forename: Frédérique
authors.initials: F
authors.lastname: Loiseau
authors.forename: Guillaume
authors.initials: G
authors.lastname: Izzet
authors.forename: Anna
authors.initials: A
authors.lastname: Proust