Synthesis and characterization of poly(1,3-phenylene)-based polyradicals carrying cyclic aminoxyls
作者:Hiroyuki Oka、Tomoki Tamura、Yozo Miura、Yoshio Teki
DOI:10.1039/b100060h
日期:——
The synthesis and magnetic properties of poly(2,2,4,4-tetramethyl-N-yloxy-1,4-dihydro-2H-3,1-benzoxazine-6,8-diyl-1,3-phenylene)
(4) are described. Polyradical 4 was prepared by the Pd-catalyzed cross-coupling
reaction of 6,8-dibromo-2,2,4,4-tetramethyl-1,4-dihydro-2H-3,1-benzoxazine
and bis(trimethylene) 1,3-phenylenediboronate, followed by oxidation with m-chloroperoxybenzoic
acid. The number average molecular weights of 4
determined by SEC (size exclusion chromatography) were ∼4120 (15
repeating units), and the spin concentrations determined by EPR were
up to 0.75 spin per repeating unit. The EPR spectrum of 4 in a toluene glass matrix showed the ΔMs = 2
forbidden transition at g = 4.0. A Curie plot
of the ΔMs = 2 signal intensity vs.
1/T gave a straight line, suggesting that the polyradical is
in a triplet ground state or a nearly degenerate singlet–triplet state.
聚(2,2,4,4-四甲基-N-基氧基-1,4-二氢-2H-3,1-苯并恶嗪-6,8-二基-1,3-亚苯基)的合成及磁性能
(4) 进行了描述。多自由基4是通过Pd催化交叉偶联制备的
6,8-二溴-2,2,4,4-四甲基-1,4-二氢-2H-3,1-苯并恶嗪的反应
和双(三亚甲基)1,3-亚苯基二硼酸酯,然后用间氯过苯甲酸氧化
酸。数均分子量4
通过 SEC(尺寸排阻色谱法)确定为 ∼4120(15
重复单元),并且由 EPR 确定的自旋浓度为
每个重复单元最多旋转 0.75 次。甲苯玻璃基质中 4 的 EPR 光谱显示 ΔMs = 2
g = 4.0 时禁止跃迁。居里图
ΔMs = 2 信号强度与
1/T 给出了一条直线,表明多自由基是
处于三重态基态或近简并的单重态-三重态。