Preparation and photoluminescence characteristics of polysiloxane pendant tris(2,2′‐bipyridine)ruthenium (II) complex

Polysiloxanes containing pendant tris(2,2′‐bipyridine)ruthenium(II) complex (Ru(bpy)3 2+ ) were prepared by reaction of polysiloxane‐pendant 2,2′‐bipyridine (PSiO‐bpy) with cis‐Ru(bpy) 2 Cl 2 . In methanol solution, the polymer pendant Ru(bpy)3 2+ showed absorption maximum at 456nm and emission maximum at around 609nm, both of which are shifted to longer wavelength than the monomeric Ru(bpy) 3 2+ . The lifetime τ 0 of the excited polymer complex with low Ru(bpy)3 2+ content was almost the same as that of the monomeric one in methanol (830ns), but τ 0 of the polymer with higher complex content was shorter because of a concentration quenching. In a solid state, τ 0 was much shorter (306–503ns) than that in a methanol solution contrary to the conventional polymeric system. Higher complex content in the polymer film caused higher glass transition temperature (Tg), but shorter τ 0 . These results indicate concentration quenching in the polymer film. The excited polymer pendant Ru(bpy)3 2+ was quenched by oxygen, and the relative emission intensity followed the Stern‐Volmer equation. In a methanol solution the quenching rate constant (k q ) was the same order of magnitude as the monomeric complex, and independent of the complex content in the polymer. In a film, k q was higher for the polymer with higher complex content.