Photophysical Properties of Soluble Polypyrrole−Polypyridyl−Ruthenium(II) Complexes

The photophysical properties of polypyridyl ruthenium(II) complexes substituted by pyrrole groups and of their corresponding soluble polymers synthesized either by electrooxidative or photoredox techniques are investigated. While their spectral properties and the temperature dependence of their lifetime are similar and close to that found for the parent [Ru(bpy) 3 ] 2+ complex, the emission quantum yields (Φ L ) and the time-resolved emission decays are strongly affected by the polymer structure. Most of the polymers are characterized by a nonexponential emission decay that can be satisfactorily analyzed globally over different temperature in the framework of a distribution of decay rates. An important decrease in Φ L along with the increase of the width of the distribution of decay rates occurs as the degree of cross-linking is increased. The 3 MLCT excited states features are also substantially dependent on the length of the alkyl linkage between the pyrrole group and the Ru(II) complex as well as on the synthetic method of polymerization used. Furthermore, the accessibility of the excited states to quenchers as methyl-viologen (electron withdrawer) or N -methylphenothiazine (electron donor) is not significantly affected by the polymer structure indicating that the un-cross-linked polymers seem to adopt an extended coil-like structure. Using the photophysical data, attempts were made to obtain insights into the polymer architecture.