Improved recognition of alkylammonium salts by ion pair recognition based on a novel heteroditopic pillar[5]arene receptor

A novel pillar[5]arene-based heteroditopic receptor for ion pair recognition of alkylammonium salts with different alkyl chain lengths and different counterions was prepared, which showed the best association constant enhancement (71 times) to n-BuNH3+Cl− compared with monotopic receptor 1,4-dimethoxypillar[5]arene over corresponding Br− and CF3COO− salts in chloroform.