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'-H(4)bptc) in the presence of pyridyl ligands yielded three isomorphous 3D metal-organic coordination polymers formulated as [Cu-2(2,2',4,4'-bptc)(L)(x)]center dot 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 [Cu-2(COO)(4)] motif and the twisted Pi-shaped 2,2',4,4'-bptc serve as dissimilar 4-connected SBUs to generate a 3D [Cu-2(2,2',4,4'-bptc)] mother framework with the PtS topology, which selectively accommodates pyridine or bis(pyridyl) ligands of appropriate size.