Interaction between dyes and polyelectrolytes, 14. Triplet energy transfer in a cationic dye‐polyanion system

Abstract

AbstractPolymers with different fractions of azobenzene residues were prepared by radical copolymerization of methacrylic acid with 4′‐phenylazomethacrylanilid. The triplet excitation energy transfer from methylene blue (1) to the azobenzene residues in the polymers was investigated by using the 1‐photosensitized cis → trans isomerization of the azobenzene residue. The efficiency of the triplet excitation energy transfer from 1 to 4‐(4′‐phenylazoanilinocarbonyl)butanoic acid (4) as a monomer model compound. The number of azobenzene residues per polymer molecule and the molecular weight of the polymer were important factors for the efficient triplet excitation energy transfer. On addition of NaCl the energy transfer efficiency was lowered, suggesting that the binding of 1 to the polymer by electrostatic forces plays an important role. Binding of 1 to the polymers was investigated spectrophotometrically. Correlation with the binding of 1 to the polymers and the efficiency of triplet excitation energy transfer between 1 and azobenzene residues in the polymers is discussed.