Poly[(p-ethynylphenyl)hydrogalvinoxyl] and its polyradical derivative with high spin concentration

[4-[(3,5-Di-tert-butyl-4-hydroxyphenyl) (3,5-di-tert-butyl -4-oxocyclohexa-2,5-dien-1-ylidene) -methyl]pheny l ]acetylene (6), was synthesized and polymerized to yield a solvent-soluble polyacetylene poly-[[4-[3,5-di-tert -butyl-4-hydroxyphenyl) (3,5-di-tert-butyl-4 -oxocyclohexa-2,5-dien-1-ylidene) methyl]phenyl ] acetylene] (5a). The polymer gave its polyradical derivative 5b through the chemical oxidation with active PbO₂. 5b was stable, whose spin concentration could be increased up to 4.8 × 10²³ spins per molar monomer unit. ESR analysis indicated localization of unpaired electrons in the galvinoxyl residue. ESR analysis also suggested an exchange-narrowing and interpolymer dipole-dipole interaction.