The 2D–3D networks with infinite channels or difform chains of copper(II) complexes via weak non-covalent interactions

A series of new copper(II) complexes with pyridine–carboxylate ligands: [Cu2(m-Cl)2(pda)2][Cu(MeOH)(H2O)4]$H2O (1), [CuBr(pda) (MeOH)]2[Cu(H2O)5]$MeOH (2), [Cu2(m-Br)2(pda)2][Cu(H2O)4]$[CuBr2(H2O)2] (3) and [CuNa2(m-sna)2]$4H2O (4) (H2pdaZpyridine-2, 6-dicarboxylic acid, H2snaZ2-sulfinonicotinic acid), have been synthesized and structurally characterized. The weak non-covalent interactions of p–p stacking and hydrogen bonding between the pyridine–carboxylate ligands extend complexes 1–4 into supramolecular architectures, where complexes 1 and 3 possess 2D networks with wave-like chains or straight chains, while complexes 2 and 4 show 2D layers and 3D networks with infinite 1D channels, respectively. The polycrystalline powder EPR spectra of complexes 1, 3 and 4 indicate that their unpaired electrons are placed in dx2Ky2 or dz2 orbitals of the ground state of Cu(II). The UV/vis, IR spectra and TG analyses for complexes 1–4 are also discussed. q 2005 Elsevier B.V. All rights reserved