MOLECULAR DESIGN, SYNTHESIS, AND MAGNETIC CHARACTERIZATION OF POLY (PHENYLACETYLENE) WITH PI-TOPOREGULATED PENDANT NITRONYL NITROXIDE RADICALS AS MODELS FOR ORGANIC SUPERPARAMAGNETS AND FERROMAGNETS

The present article describes the synthesis and magnetic properties of poly(phenylacetylene) (3) with pi-toporegulated pendant stable 4,4,5,5-tetramethylimidazolin-3-oxide-1-yloxyl radicals topologically participating in the pi-conjugated system of poly(phenylacetylene). Polyradical 3 was prepared by the condensation reaction of poly(p-ethynylbenzaldehyde) with 2,3-bis (hydroxylamino)-2,3-dimethylbutane followed by oxidation with lead dioxide. The spin concentration of 3 determined by the ESR spectroscopic method was 1.1 x 10(21) spins/g. This value approximately corresponds to 0.5 unpaired electron spin per the repeating unit. A powder ESR spectrum of 3 gave a 100% Lorentzian single line showing spin-exchange narrowing. The vibrating sample magnetometer (VSM) measurement of 3 afforded a straight line with a positive slope, suggesting that 3 has predominant paramagnetic properties within an experimental error.