Folding-Induced Through-Space Magnetic Interaction of Poly(1,3-phenyleneethynylene)-Based Polyradicals

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• 作者：Takashi Kaneko ; Hiromasa Abe ; Masahiro Teraguchi ; Toshiki Aoki
• 刊名：Macromolecules
• 出版年：2013
• 出版时间：April 9, 2013
• 年：2013
• 卷：46
• 期：7
• 页码：2583-2589
• 全文大小：400K
• 年卷期：v.46,no.7(April 9, 2013)
• ISSN：1520-5835

文摘

We synthesized poly(1,3-phenyleneethynylene)s bearing galvinoxyl moieties. The absorption ratio of the anion form in 1 M KOH methanol solution between 309 and 294 nm (A₃₀₉/A₂₉₄) decreased with increasing degree of polymerization. The wide-angle X-ray scattering of the powder, which was prepared by precipitation in dilute hydrochloric acid solution from the anion form in 1 M KOH methanol solution, showed a crystalline peak at 2胃 = 28掳. Polymers in which the chiral diethynyl-1,1鈥?binaphthyl moiety was inserted into the poly(1,3-phenyleneethynylene) chain were synthesized, and clear Cotton effects were observed in the absorption region of the galvinoxyl anion chromophore in the CD spectra taken in 1 M KOH鈥揗eOH solution, indicating an excess of one-handed folded helical conformation. A relatively strong antiferromagnetic interaction was observed for the polyradicals prepared by precipitating the anionic form from alkaline methanol solution accompanied with oxidation using aqueous K₃Fe(CN)₆ solution. These observations suggest that the relatively strong antiferromagnetic interaction of the polyradicals was caused by the close packing between galvinoxyl radicals induced by the formation of the folded helical structure.