A novel self-penetrating metal–organic open framework containing unusual triple-stranded molecular braid and septuple helices

Self-assembly of a long V-shaped 4,4′-oxydiphthalate (odpa) ligand and copper salt in the presence of a linear bidentate ligand affords a unique self-penetrating metal–organic open framework [Cu2(odpa)(bpy)2] (1) (bpy = 4,4′-bipyridine), exhibiting an unprecedented binodal four-connected (64.82)2(62.84) topology. Its structure was determined by single-crystal X-ray diffraction analysis and further characterized by elemental analyses, IR spectrum, X-ray powder diffraction, and TG analysis. Compound 1 is a novel three-dimensional (3D) guest-free porous framework containing molecular braids and septuple helices, which are particularly rare in metal–organic coordination polymers.