Synthesis and Properties of N-Arylpyrrole-Functionalized Poly(1-hexene-alt-CO)

The 1,4-polyketone derived from 1-hexene and carbon monoxide, poly(1-hexene-alt-CO) (1), can undergo PaalKnorr cyclization with substituted anilines to yield N-pyrrole-functionalized polyketones. A variety of pendant functionalities are introduced to 1, including azobenzene (6) and triarylamines (5ae). The extent of incorporation depends on the nucleophilicity of the parent aniline. Polymer 6 exhibits a UV-induced trans -> cis photoisomerization and has lower rates of photoinduced decomposition relative to parent 1. Triarylamine-containing polymers 5a-e are redox-active, forming optically active radical cations upon chemical oxidation. Compared with model N-arylpyrrole compounds 9a-e, polymers 5a-e demonstrate hypsochromic shifts in UV-vis absorptions and exhibit features between +0.5 and +1.2 V (vs Ag/AgCl) in solution-phase differential pulse voltammetry.