Selective incorporation of auxiliary organic ligands in metal-organic frameworks based on twisted Π-shaped building blocks

Hydrothermal reactions of Cu(II) salts and 2,2′,4,4′- biphenyltetracarboxylic acid (2,2′,4,4′-H₄bptc) in the presence of pyridyl ligands yielded three isomorphous 3D metal-organic coordination polymers formulated as [Cu₂(2,2′,4,4′-bptc) (L)_x]•H₂O [x = 2 for L = pyridine; x = 1 for L = bis(4-pyridyl)ethene and bis(4-pyridyl)ethane]. In the structure, the distorted paddlewheel [Cu₂(COO)₄] motif and the twisted Π-shaped 2,2′,4,4′-bptc serve as dissimilar 4-connected SBUs to generate a 3D [Cu₂(2,2′,4,4′-bptc)] mother framework with the PtS topology, which selectively accommodates pyridine or bis(pyridyl) ligands of appropriate size.