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.