A chiral M6L4 cage complex assembled from a D2h-symmetric ligand:: Self-assembly, structure, and chirality observation

Chiral M6L4 cage structures were self-assembled by mixing a D-2h-symmetric ligand with a cis end-capped (diamine)Pd(NO3)(2) complex [diamine = ethylenediamine (en), 2,2'-bipyridine (2,2-bpy), or 1,2-cyclohexanediamine (cxn)]. This self-assembly was achieved by exploiting the template effect of an aromatic guest molecule. The structures were confirmed by CSI-MS, NMR observations, and X-ray crystallographic analysis. Having C-2 molecular chirality, two diastereomers were differentiated by attaching a chiral auxiliary on Pd(II).