Anthryl-Based Poly(phenylene ethynylene)s: Tuning Optical Properties with Diels−Alder Reactions

Sol. anthryl-based conjugated poly(phenylene ethynylene)s (PPEs) have been synthesized using palladium-catalyzed Sonogashira-Hagihara cross-coupling polymn. reactions. Mol. wts. up to 3.5 × 104 g•mol-1 were obtained, making them suitable for spectroscopic soln. characterizations and thin film processing. The selective reactivity of these polymers as multidienes has been successfully demonstrated with strong dienophiles. Diels-Alder reactions proceed cleanly to completion with unhindered dienophiles such as N-alkylated maleimide derivs. TGA anal. revealed thermal retro-Diels-Alder reactions at modest temps. around 210 °C. Compared with their parent polymers, the cycloadduct polymers exhibited dramatic hypsochromic shifts of their emission and absorption maxima up to 80 nm along with a considerable quantum yield enhancement. These original anthryl-based polymers appear attractive as reactive conjugated materials whose optical properties can easily be tuned with quant. Diels-Alder reactions. [on SciFinder(R)]