Conformation-Selective Self-Assembly of Pd₆ Trifacial Molecular Barrels Using a Tetrapyridyl Ligand

A conformationally flexible tetrapyridyl ligand L was assembled separately with three cis-blocked 90° Pd^II acceptors (M1, M2, and M3) containing different blocking diamines. Surprisingly, different conformations of the donor L were arrested by the acceptors depending on the nature of the blocking amine, leading to the formation of isomeric Pd₆ barrels (B1, B2, and B3). B2 and B3 with larger windows have been used to encapsulate polyaromatic hydrocarbons.