Synthesis and characterization of new coordination polymers based on 2,3-/3,4-pyridinedicarboxylates and bispyridine ligands with structural diversity

Abstract

New coordination polymers, formulated as {bpaH2[Cu(μ-2,3-pydc)2]}n (1), [Cd(μ-2,3-pydc)(μ-bpa)0.5(H2O)2]n (2), {[Co2(μ4-3,4-pydc)2(μ-bpe)(H2O)2]·H2O}n (3) and [Cu2(pic)4(μ-4,4′-bipy)]·(4,4′-bipy)·2H2O (4) have been synthesized based on the bispyridine ligands; 1,2-bis(4-pyridyl)ethane (bpa), 1,2-bis(4-pyridyl)ethylene (bpe) and 4,4′-bipyridine (4,4′-bipy) along with dianionic 2,3- and 3,4-pyridinedicarboxylate (2,3-pydc and 3,4-pydc) and mono anionic picolinate (pic) ligands, respectively. All the complexes have been characterized by elemental and IR spectroscopy and single-crystal X-ray diffraction studies. 1 has proton transfer products of bpaH2 cations and shows 1D double chain. Using of the 2,3-pydc and 3,4-pydc ligands in 2 and 3 in the presence of Cd(II) and Co(II) ions generate 1D→2D inclined polycatenated structure in 2 and 4,5 connected {44·62·104}{44·62} 4,5T6 topology in 3, respectively. The picolinate ligand in dinuclear structure of 4 was occurred by partial decarboxylation of 2,3-pydcH2 in the process of the solvothermal reaction. 4,4′-Bipyridine molecules act as both a template via rare weak C–H⋯N interaction and a bridge between Cu(II) centers in the self-assembly process of supramolecular structure of 4. Thermal decomposition behavior of complexes and luminescent property of 2 are also presented herein.