Supramolecular Catalysis by Carboxylated Pillar[n]arenes

Pillar[n]arenes constitute the most recognizable macrocyclic compounds discovered recently. So far, research has been focused on their binding properties, while the catalytic properties were poorly explored. Herein we present the study of the binding as well as the catalytic properties of pillar[5]‐ and pillar[6]arenes functionalized with carboxylic groups in water. We show that electrostatic stabilization is not the main driving force during the binding, however, it is crucial for catalysis. The macrocycles promote the hydrolysis of a wide variety of hydrazones, and their catalytic activity, in essence, is determined by the barrier of the passage of the substrate through the macrocyclic cavity. This opens up new perspectives for these macrocycles that could make a strong competition to traditional supramolecular catalysts such as cyclodextrins or cucurbiturils.