Complexation Selectivities of Pillar[5]arenes with Primary Ammonium Salts

The complexation of alkyl-substituted pillar[5]arenes with primary ammonium salts is investigated. 1,4-Bis- （methoxy）pillar[5]arene （MeP5） can form strong complexes with the primary ammonium salts in CDC13. However, 1,4-bis（ethoxy）pillar[5]arene （EtP5） shows weak interaction with these guests, and 1,4-bis（butoxy）pillar[5]arene （BuP5） can not form such a complex at all. These results indicate that the modified alkyl chains of pillar[5]arene play an important role in the complexation selectivity.