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 CDCl3. 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.