Synthesis and Reductive Complexation Properties of a Cone‐Configurated Tetra[p‐(tert‐butyl)]calix[4]arene incorporating bipyridyl and pyridine subunits. NMR characterization and crystal structure of its chiral copper(I) complex

The hetero‐armed p ( tert ‐butyl)calix[4]arene 1 was synthesized by a stepwise procedure. This ligand presented a very strong complexing behavior towards Cu 1 , giving the chiral complex 2 and parent species when reacted with Cu II salts. High‐resolution NMR techniques were employed for the characterization of 2 , demonstrating notably exchange processes between its two enantiomeric forms. The racemic nature of 2 was confirmed by X‐ray crystal‐structure analysis.