高等学校化学学报

高等学校化学学报 ›› 2001, Vol. 22 ›› Issue (S1): 177.

• 研究论文 • 上一篇    下一篇

5,17-二(N-叔丁基-N-羟胺基)-11,23-二溴-25,26,27,28-四甲氧基杯[4]芳烃的合成、晶体结构及其氧化物的ESR研究

王琪, 王如骥, 李勇, 吴国是   

  1. 清华大学化学系, 北京 100084
  • 收稿日期:2001-09-07 出版日期:2001-12-31 发布日期:2001-12-31
  • 通讯作者: 李勇(1961年出生),男,博士,副教授,从事磁共振化学研究.

The Synthesis, Crystal Structure of 5,17-Di-(N-p-tert-butyl hydro-xyamino)-11,23-di-bromo-25,26,27,28-tetrainethoxycalix[4] arene and ESR Studies of Its Oxide

WANG Qi, WANG Ru-Ji, LI Yong, WU Guo-Shi   

  1. Department of Chemistry, Tsinghua University, Beijing 100084, China
  • Received:2001-09-07 Online:2001-12-31 Published:2001-12-31

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摘要：

由对-四溴-四甲氧基杯[4]芳烃(Ⅰ)制备得到5,17-二(N-叔丁基-N羟胺基)-11,23-二溴-25,26,27,28-四甲氧基杯[4]芳烃(Ⅱ),并对其进行了红外光谱、核磁氢谱、质谱、晶体结构的研究.X射线衍射晶体结构分析 表明化合物Ⅱ为部分雄型构象.晶体属单斜晶系C2/c空间群.a=3.225 5 (7) nm, b=1.439 4 (3) nm,c=2.175 3 (5) nm, β=110.210 (9)°, V=9.478 (3) nm3, Z=8, R=0.073 8.对位有羟胺基取代的两个苯环为顺式,分子内不同羟胺基之间的N…H接触距离分别为0.201 5 nm和0.190 6 nm,对应的∠N…H-O分别为153.5°和150.3°,表明存在着分子内氢键N…H-O.电子顺磁共振(ESR)实验表明空气中化合物Ⅱ在溶液里容易氧化生成相应的双氮氧自由基,分子内存在磁偶极相互作用和较弱的自旋交换相互作用.

关键词: 杯芳烃, 合成, 晶体结构, 电子顺磁共振

Abstract:

5,17-Di-(N-p-tert-butyl-N-hydroxyamino)-11,23-di-bromo-25,26,27,28-tetramethoxycalix[4] arene (Ⅱ),which is a precursor of nitroxide radical is synthesized by selective halogen-lithium exchange reaction of 5,11,17,23-tetrabromo-tetramethoxycalix[4]arene (Ⅰ) with n-BuLi and 2-methyl-2-nitrosopropane (MNP). Compound Ⅱ is characterized by IR lH NMR mass spectrum and elementary analysis. The crystal structure of compound Ⅱ has been determined. Crystals are monoclinic, space group C2/c (No. 15) with a=3.225 5 (7) nm, b=1.439 4 (3) nm, c=2.175 3 (5) nm, β=110.210 (9)°, V=9.478 (3) nm3 and Z=8, with final residuals R=0.073 8 and Rw=0.160 3. According to X-Ray analysis compound Ⅱ is presented in a flattened partial cone conformation, which is less common for calix[4]arenes in solid. The two opposite phenyl rings bearing hydroxyamino groups are in an syn orientation and each molecule exhibits two intramolecular hydrogen bonds, N…H-O, which can also be deduced from IR and NMR spectra. The bond length of N…H is about 0.2 nm and bond angle of N…H-O is about 150°. Compound Ⅱ in solution is easily oxidized to a stable nitroxide biradical and electron spin resonance (ESR) observation reveals that there exists magnetic dipole-dipole interaction and weak spin exchange interaction between the two unpaired electrons in the molecule.

Key words: calix[4]arene, synthesis, crystal structure, electron spin resonance

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