Helical polyacetylenes carrying 2,2,6,6-tetramethyl-1-piperidinyloxy and 2,2,5,5-tetramethyl-1-pyrrolidinyloxy moieties: Their synthesis, properties, and function

2,2,6,6-Tetramethyl-1-piperidinyloxy (TEMPO)- and 2,2,5,5-tetramethyl-1-pyrrolidinyloxy (PROXYL)-containing (R)-1-methylpropargyl TEMPO-4-carboxylate (1), (R)-1-methylpropargyl PROXYL-3-carboxylate (2), (rac)-1-methylpropargyl PROXYL-3-carboxylate (3), (S)-1-propargylcarbamoylethyl TEMPO-4-carboxylate (4), and (S)-1-propargyloxycarbonylethyl TEMPO-4-carboxylate (5) (TEMPO, PROXYL) were polymerized to afford novel polymers containing the TEMPO and PROXYL radicals at high densities. Monomers 1-3 and 5 provided polymers with moderate number-average molecular weights of 8200-140,900 in 49-97% yields in the presence of (nbd)Rh+[eta(6)-C6H5B-(C6H5)(3)], whereas 4 gave no polymer with this catalyst but gave polymers possessing low Mu (3800-7500) in 56-61% yield with [(nbd)RhCl](2)-Et3N. Poly(l), poly(2), and poly(4) took a helical structure with predominantly one-handed screw sense in THF and CHCl3 as well as in film state. The helical structure of poly(l) and poly(2) was stable upon heating and addition of MeOH, whereas poly(4) was responsive to heat and solvents. All of the free radical-containing polymers displayed the reversible charge/discharge processes, whose capacities were in a range of 43.2-112 A h/kg. In particular, the capacities of poly(2)-poly(5)-based cells reached about 90-100% of the theoretical values regardless of the secondary structure of the polymer, helix and random. Poly(l), poly(2), and poly(4) taking a helical structure exhibited better capacity tolerance towards the increase of current density than non-helical poly(3) and poly(5) did. (c) 2007 Wiley Periodicals, Inc.