Acta Chimica Sinica ›› 2012, Vol. 70 ›› Issue (17): 1775-1778.DOI: 10.6023/A12060296 Previous Articles     Next Articles



韩成友, 张子彬, 池小东, 张明明, 喻国灿, 黄飞鹤   

  1. 浙江大学化学系 杭州 310027
  • 投稿日期:2012-06-11 发布日期:2012-07-17
  • 通讯作者: 黄飞鹤
  • 基金资助:
    项目受国家自然科学基金(Nos. 20834004和91027006)资助.

Synthesis of 1,4-Bis(n-propoxy)pillar[7]arene and Its Host-guest Chemistry

Han Chengyou, Zhang Zibin, Chi Xiaodong, Zhang Mingming, Yu Guocan, Huang Feihe   

  1. Department of Chemistry, Zhejiang University, Hangzhou 310027, China
  • Received:2012-06-11 Published:2012-07-17
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Nos. 20834004 and 91027006).

Pillar[n]arenes, as a new type of macrocyclic hosts, have attracted more and more attention in recent years. Their repeating units are connected by methylene bridges at the para-positions so they have a pillar architecture, which is different from the basket-shaped structure of meta-bridged calixarenes. Herein, 1,4-Bis(n-propoxy)pillar[5]arene (P5), 1,4-bis(n-propoxy)pillar[6]arene (P6) and 1,4-bis(n-propoxy)pillar[7]arene (P7) were synthesized from the condensation of 1,4-di(n-propoxy)-2,5-bis(methoxymethyl)benzene using p-toluenesulfonic acid as the catalyst in dichloromethane. They were characterized by 1H NMR, 13C NMR and mass spectrometry. They had different 1H NMR spectra but similar 13C NMR spectra. The diameter of the internal cavity of P5 is ca. 4.6 Å, similar to those of cucurbit[6]uril (ca. 5.8 Å) and α-cyclodextrin (ca. 4.7 Å). The diameter of the internal cavity of P6 is ca. 6.7 Å, similar to those of cucurbit[7]uril (ca. 7.3 Å) and β-cyclodextrin (ca. 6.0 Å). The diameter of the internal cavity of P7 is ca. 8.7 Å, similar to those of cucurbit[8]uril (ca. 8.8 Å) and γ-cyclodextrin (ca. 7.5 Å). The host-guest binding properties of them were investigated with n-octyltriethyl ammonium hexafluorophosphate G as a model guest. P6 showed complexation with G while weak complexation was observed between G and P5, but no complexation occurred between P7 and G. The 1H NMR spectrum of an equimolar solution of P6 and G in chloroform-d showed only one set of peaks, indicating fast-exchange complexation between P6 and G on the 1H NMR time scale at 22 °C. A mole ratio plot indicated that the complexation stoichiometry was 1:1 between P6 and G. This was further confirmed by a low resolution electrospray ionization mass spectroscopy peak at m/z 1451.7 corresponding to [P6G - PF6]+. The association constant of the 1∶1 complex P6G in chloroform-d was determined to be (740±86) L·mol-1 by a proton NMR titration. These experiments demonstrate that G fits the cavity of P6 while it is too big for the cavity of P5 and too small for the cavity of P7.

Key words: macrocycles, host-guest chemistry, supramolecular chemistry, pillararenes, self-assembly