Poly(1,2-phenylenevinylene)s bearing nitronyl nitroxide and galvinoxyl at the 4-position: π-Conjugated and non-Kekulé-type polyradicals with a triplet ground state

Poly[4-(4′,4′,5′,5′-tetramethyl-3′-oxido- 1′-oxylimidazolinium-2′-yl)-1,2-phenylenevinylene] (1) and poly[4-[(3,5-di-tert-butyl-4-oxyphenyl)(3,5-di-tert-butyl-4-oxocyclohexa-2,5- diene-1-ylidene)methyl]-1,2-phenylenevinylene] (2) were synthesized via the polymerization of 2-bromo-4-[1′,3′-bis(tert-butyldimethylsiloxy)-4′,4′, 5′,5′-tetramethylimidazolin-2′-yl]styrene (10) and 2-iodo-4-[(3,5-di-tert-butyl-4-acetoxyphenyl)(3,5-di-tert-butyl-4-oxocyclohexa- 2,5-dien-1-ylidene)methyl]styrene (12), respectively, using a palladium catalyst. Their spin (radical) concentration could be increased beyond 0.9 per molar monomer unit, and they were stable even in air at room temperature. The polyradicals satisfied an alternant but non-Kekulé-type π-conjugated structure and displayed a triplet ground state or an intramacromolecular ferromagnetic spin coupling in the SQUID magnetization measurement.