Molecular design,synthesis, and magnetic characterization of poly(phenylacetylene) with pi-toporegulated pendant nitronyl nitroxide radicals as models for organic superpara- and ferromagnets |
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Authors: | Yozo Miura Kunihiko Inui Fumihiko Yamaguchi Makoto Inoue Yoshio Tek? Takeji Takui Koichi Itoh |
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Abstract: | 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 × 1021 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. |
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Keywords: | organic magnetic material polyradical stable radical conjugated polymer ESR magnetic property |
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