Crystal Structure and Host-Guest Binding Ability of Three Types of Pillar[5]arenes

A systematic research of the structural characterization and the host-guest binding abilities between three types of pillar[5]arenes 3-5 (3 for Structure Type I, 4 for Structure Type II and 5 for Structure Type III) is carried out by H-1 NMR measurements and X-ray study. The results show that the configurations or symmetry of their cavities not only have large difference in these three types of pillar[5]arenes, but also have more or less variations even in the same structure type or the same host locked different guests such as crystals of 3a-3b, 4a-4d. On the other hand, the complexation behavior of pillar[5]arenes with 1,4-dibromobutane (DBB) is affected by the different symmetrical structure or substituents on the rings.