Conjugated Polymers Carrying Stable Radicals and Their Spin Control

用Vilsmeier法和有机锂试剂分别合成了乙炔单体（3，5-二叔丁基-4-羟基苯基）乙炔和对乙炔基苯基羟基galvinoxyl，研究了它们的电子结构和磁性.这些单体在复分解或威尔金森催化剂作用下聚合，得到了分子量约为1000的聚乙炔衍生物聚[（3，5-二叔丁基-4-羟基苯基）乙炔]（1）和聚（对乙炔基苯基羟基galvinoxyl）（2）。10^4聚合物可溶于普通有机溶剂中，用PbO_2或碱性K_3Fe（CN）_6进行非均相化学氧化可转化为相应的共轭聚合物自由基。通过调节氧化条件，得到了自旋浓度极高的聚自由基2。通过紫外光电子能谱（UPS）和溶液ESR谱分析了这些自由基的电子状态，发现它们在溶液中和固体中都是稳定的，这是由于取代基的共振稳定和/或空间位阻效应。UPS检测了这些多自由基中沿主链存在的显著的π共轭沿着。电离阈值的降低和升高可以用侧链取代基的空间效应来解释。氧化产物1的超精细结构的ESR谱表明，苯氧基自由基通过聚乙炔主链在约100 - 200 ℃的温度下形成共轭物。7个单体单元作为“中性孤子”。从ESR信号强度随温度的变化关系中观察到未成对电子之间的反铁磁相互作用，揭示了以聚乙炔为骨架的聚自由基的磁性既与主链上沿着的共轭电子态有关，又与侧链自由基取代基的特殊排列有关。

Synthesis and magnetic properties of new conjugated polymers carrying stable radicals were studied in connection with their electronic structure.Acetylene monomers, (3, 5-di-tert-butyl-4-hydroxyphenyl) acetylene and p-ethynylphenyl hydrogalvinoxyl, were synthesized using Vilsmeier method, and organolithium reagents, respectively. These monomers were polymerized with metathesis or Wilkinson catalyst to yield their polyacetylene derivatives, poly[(3, 5-di-tert-butyl-4-hydroxyphenyl)acetylene] (1) and poly (p-ethynylphenyl hydrogalvinoxyl) (2), with molecular weight of ca. 10^4. The polymers were soluble in common organic solvents and converted to the corresponding conjugated polyradicals via heterogeneous chemical oxidation using PbO_2 or alkaline K_3Fe (CN)_6. The polyradical 2 with extremely high spin concentration were obtained by regulating the oxidative conditions. The polyradicals were quite stable in solution and even in the solid state because of resonance stabilization and/or a steric effect of the substituens.Electronic state of these polyradicals were analyzed using ultraviolet photoelectron spectroscopy (UPS) and solution ESR spectra. The existence of significant pi-conjugation along the main chain in these polyradicals were examined by UPS. Decrease and increase in ionization threshold could be explained by the steric effect of sidechain substituent. ESR spectra with hyperfine structure for the oxidized 1 indicated that the phenoxy radical conjugates through the polyacetylene main chain over ca. 7 monomer units as a "neutral soliton". Antiferromagnetic interaction between the unpaired electrons was observed in 1 and from the temperature dependency of the ESR signal intensity.This research project revealed that magnetic properties of polyradical with polyacetylene backbone depend both on conjugated electronic state along main chain and on special arrangement of sidechain radical substituent.