Poly(<i>p</i>‑phenylenediethynylene phosphine)s and Related π‑Conjugated Phosphine–Diyne Polymers: Synthesis, Characterization and Photophysical Properties

Despite the considerable synthetic challenge, polymers that incorporate phosphorus atoms within or adjacent to a π-conjugated backbone framework are of interest due to the ability to modulate the photophysical properties of the polymer based on the chemical environment at phosphorus. We report the synthesis and characterization of poly­(<i>p</i>-phenylenediethlynylene phosphine)­s, <b>1a</b>–<b>1e</b>, a new class of σ–π conjugated polymer. Polymers <b>1a</b>–<b>1e</b> were prepared by a Ni-catalyzed coupling of dialkynes with phenyldichlorophosphine in the presence of excess triethylamine and have molecular weights (<i>M</i>_w) up to 12,000 g mol^–1 (vs. polystyrene). While the polymers <b>1b</b>–<b>1e</b> are nonfluorescent, blue fluorescence is observed upon oxidation of the phosphorus centers (Φ_soln = 0.12–0.28). Polymers <b>1b</b>·O–<b>1e</b>·O also exhibit yellow/green fluorescence in the solid state (Φ_solid = 0.04–0.08). These results introduce a fascinating new class of main group-containing macromolecule and lay the groundwork for their utilization in sensory applications and/or their incorporation into optoelectrical devices