Photophysical properties of soluble polypyrrole-polypyridyl-ruthenium(II) complexes

The photophysical properties of polypyridyl ruthenium(II) complexes substit uted by pyrrole groups and of their corresponding soluble polymers synthesi zed either by electrooxidative or photoredox techniques are investigated. W hile their spectral properties and the temperature dependence of their life time are similar and close to that found for the parent [Ru(bpy)(3)](2+) co mplex, the emission quantum yields (Phi (L)) and the time-resolved emission decays are strongly affected by the polymer structure. Most of the polymer s are characterized by a nonexponential emission decay that can be satisfac torily analyzed globally over different temperature in the framework of a d istribution of decay rates. An important decrease in Phi (L) along with the increase of the width of the distribution of decay rates occurs as the deg ree of cross-linking is increased. The (MLCT)-M-3 excited states features a re 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 stat es to quenchers as methyl-viologen (electron withdrawer) or N-methylphenoth iazine (electron donor) is not significantly affected by the polymer struct ure indicating that the un-cross-linked polymers seem to adopt an extended coil-like structure. Using the photophysical data, attempts were made to ob tain insights into the polymer architecture.