Host-guest complexes of a water soluble cucurbit[6]uril derivative with some dications of 1,ω-alkyldipyridines: 1H NMR and X-ray structures

• 来源期刊: 中国科学B辑（英文版）
• 年，卷（期）: 2009,（4）
• 页码范围: 475-482
• 页数: 8页
• 语种: 英文
• DOI: 10.1007/s11426-009-0089-9

摘要

Interactions between s symmetrical tetramethyl-substltuted cucurbit[6]uril (host: TMeQ[6]) and 1,ω-alkylenedipyridine (ω = 2, 4, 6, 8,10) dlcationlc guests were investigated using1H NMR spectroscopy and single crystal X-ray crystallography. In these Inclusion complexes, combined cavity and portal binding in TMeQ[6] were observed, and the length of the bridged alkylene was found to play an impor-rant role not only in balancing the overall hydrophilic/hydrophobic interaction between the host and the guest, but also in defining the structure of the resulting Inclusion complexes. For the guest 1,2-ethylenedipyridine (Edpy), TMeQ[6] includes a positively charged pyridine ring of Edpy to form an unsymmetrical inclusion complex; for the guest 1,4-butylenedipyridine (Bdpy), TMeQ[6] includes a po-sitively charged pyridine ring of Bdpy, but the different competitive interactions in and between the re-lated inclusion complexes could lead to a fast exchange between the hosts and guests. For the guests with longer bridge chains, such as 1,6-hexamethylenedipyridine (Hdpy) or 1,8-octylenedipyridine (Odpy), a stable pseudorotsxane inclusion complex is formed by combining the hydrophobic cavity and the outer portal dipole-ion interactions. However, for 1,10-decatylenedipyridine (Ddpy), the two TMeQ[6] host molecules include the two end pyridine rings of Ddpy and form a dumbbell inclusion complex.