LUMINESCENCE QUENCHING OF PARTIALLY QUATERNIZED POLY(1-VINYLIMIDAZOLE)-BOUND RUTHENIUM(II) COMPLEX IN METHANOL

Metallopolymers in which bis(2,2'-bipyridine)ruthenium(II) complexes a re coordinated to imidazolyl residues on partially quaternized poly(1- vinylimidazole) having different degree of quaternization (RuQPIm) wer e synthesized. The luminescence quenching of the photoexcited RuQPIms with various alkylviologens having different length of alkyl group was investigated in MeOH. In quenching of RuQPIm with methylviologen grou p (MV2+), the efficiency of quenching decreases with increasing degree of quaternization. This was attributed to the electrostatic repulsion between the MV2+ species and the quaternized imidazolium residue on t he polymer backbone and steric hindrance of the alkyl side chain. Furt hermore, the efficiency of quenching depends on the length of the alky l group in viologen. These results suggest that the alkyl side chain o n the polymer backbone exerts steric hindrance at low degree of quater nization and van der Waals interaction at high degree of quaternizatio n.