Copolyfluorenes containing polymethine dyes in the main chain: synthesis and photophysical properties

Despite the huge progress in the synthesis of small organic fluorophores and inorganic materials emitting in the red and near-infrared region, the synthesis of π-conjugated polymers with fluorescence in this range remains a challenging task. A series of fluorene-polymethine dye copolymers were synthesized by the Suzuki-Miyaura coupling polycondensation using cyanine, keto-cyanine, and squaraine comonomers, which exhibit fluorescence at ca. 500−700 nm. These polymers exhibit both green to red or near-infrared absorption and emission attributed to polymethine dyes, and absorption and emission bands corresponding to polyfluorene (at ca. 380 and 420−470 nm, respectively). The influence of pH on the UV-Vis absorption and luminescence spectra of the copolymers in solution was studied.