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(μ-Cl)2(pda)2][Cu(MeOH)(H2O)4]·H2O (1), [CuBr(pda)(MeOH)]2[Cu(H2O)5]·MeOH (2), [Cu2(μ-Br)2(pda)2][Cu(H2O)4]·[CuBr2(H2O)2] (3) and [CuNa2(μ-sna)2]·4H2O (4) (H2pda=pyridine-2,6-dicarboxylic acid, H2sna=2-sulfinonicotinic acid), have been synthesized and structurally characterized. The weak non-covalent interactions of π-π 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 dx2−y2 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.