Chin. J. Org. Chem. ›› 2014, Vol. 34 ›› Issue (8): 1652-1661.DOI: 10.6023/cjoc201402033 Previous Articles     Next Articles



魏金燕a, 徐立进a, 龚汉元b   

  1. a 中国人民大学化学系 北京 100872;
    b 北京师范大学化学学院 北京 100875
  • 收稿日期:2014-02-27 修回日期:2014-03-12 发布日期:2014-04-10
  • 通讯作者: 徐立进,龚汉元;
  • 基金资助:

Backbone Effect of Macrocycle Host Compound as Anion Receptor

Wei Jinyana, Xu Lijina, Gong Hanyuanb   

  1. a Department of Chemistry, Renmin University of China, Beijing 100872;
    b College of Chemistry, Beijing Normal University, Beijing 100875
  • Received:2014-02-27 Revised:2014-03-12 Published:2014-04-10
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Nos. 21202199, 21372258).

Two novel macrocycle hosts with flexible frameworks and cavities, cyclo[2](2,6-di(1H-imidazol-1-yl)pyridine)[2] (1,4-dimethylenebenzene) (14+) and cyclo[2](2,6-di(1H-imidazol-1-yl)pyridine)[2](1,2-dimethylenebenzene) (24+), were synthesized with high yields via cyclization reactions between 2,6-di(1H-imidazol-1-yl)pyridine and 1,4-bisbromomethyl benzene or 1,2-bisbromomethyl-benzene. Herein, the interactions between 14+ or 24+ and a series of inorganic anionic guests were studied in detail via the following methods: (1) 1H NMR spectroscopy in d6-DMSO solution; (2) electrospray ionization mass spectrometry (ESI-MS) in gas phase; (3) single crystal X-ray crystallography in solid state. It is noted that the anionic guest species has different shapes, namely anions with ball shapes like Cl-, Br-, I-; linear anion N3-; triangle or tetrahedron HSO4-. The study found that 14+ can bind more small inorganic anion species than macrocycle 24+. In addition, the result implied that when the inorganic anion guest acts as strong intermolecular hydrogen bond acceptor (i.e. anionic guest (A-) such as Cl-, or ), the associate constant (Ka) maintains Ka[24+·A-]3+>Ka[14+·A-]3+; on the contrary, when anionic guest A- (Br- or I-) is hard to form intermolecular hydrogen bonds but easy contribute to anion-π interaction, the association constants of the 1:1 (host:guest) complexes follow another trend (i.e. Ka[24+·A-]3+<Ka[14+·A-]3+ when A- is Br- or I-). It is suggested that the skeleton of macrocycle host 24+ well organize its four strong acidic imidazolium C—H bonds for effective small inorganic anion binding mainly via intermolecular hydrogen bonds; meanwhile the bigger cavity and longer distances between the strong acidic imidazolium C—H bonds of 14+ leads two possible results: (1) worse cooperation of its acidic C—H bonds weaken the intermolecular hydrogen bonding interactions for small anion complexation; (2) its more relax backbone has possible benefits of binding more anion guests. In summary, small distinctions of the backbones between 14+ and 24+ result in significantly different anion complexations, including stoichiometries, association constants, binding modes, etc. This finding will help to guide following macrocyclic anion receptor design and study.

Key words: macrocycle, backbone, non-covalent weak interactions, anion binding