Decamethyl-pillar[5]arene: Synthesis and Recognition Properties

Abstract

In this two-session experiment for an organic chemistry lab, students prepare a macrocyclic host compound�namely, a pillar[5]-arene�by means of a templated 1,4-dimethoxybenzene/formaldehyde cyclo-oligomerization (session 1), and then, they explore its molecular recognition properties toward the 1,8-diaminooctane guest with the aid of 1 H NMR spectroscopy (session 2). The acid-catalyzed synthesis of decamethyl-pillar[5]arene provides, in good yield, a product sufficiently pure to be directly used in the subsequent NMR titration experiment. The two-session experiment targets advanced chemistry students, whereas the 4 h synthesis of the macrocycle (session 1) may be included in an introductory organic chemistry laboratory course. This experiment links concepts spanning from classical S E Ar reactions to macrocycle synthesis down to host−guest chemistry, NMR spectroscopy, and data treatment, providing a useful connection between organic chemistry synthesis and supramolecular chemistry.