Interlocking of molecular rhombi into a 2D polyrotaxane network via pi-pi interactions. Crystal structure of [Cu2(bpa)2(phen)2(H2O)]2.2H2O (bpa2- = biphenyl-4,4'-dicarboxylate, phen = 1,10-phenanthroline).

In the solid state, interlocking of the lateral phen ligands at the acute angle sites of the molecular [Cu2(bpa)2-(phen)2(H2O)]2 rhombi via aromatic pi-pi stacking interactions into the cavities of the adjacent rhombi generates laminated polyrotaxanes that are further assembled into a 3D network via similar interactions between the phen ligands at the obtuse angle sites.