Unprecedented cadmium(II) complex with (44 · 66) net topology and in situ ligand synthesis

Hydrothermal reactions of 4,4′-bipyridine-2,2′-dicarboxylic acid (H2BPDCA) with Cu(II) and Cd(II) nitrate salts result in the formation of two complexes [Cu(2,4-Hpydca)2(H2O)2] (1) and [Cd(2,4-pydca)]n (2) with pyridine-2,4-dicarboxylate (2,4-pydca2−), rather than BPDCA2−, as ligand, namely the in situ transformation of H2BPDCA to H2pydca occurred under the hydrothermal conditions. Complex 1 has been previously reported from different synthetic route, however, complex 2 is the first binodal 5-connecting 3D framework with unprecedented (44 · 66) net topology. The results provide a new strategy for in situ ligand synthesis and construction of coordination polymers with specific topology.