Six new coordination polymers based on a tritopic pyridyldicarboxylate ligand: structural, magnetic and sorption properties

Abstract

Using a rigid ligand, pyridine-3,5-bis(phenyl-4-carboxylic) acid (H₂L), six new coordination polymers have been synthesized under solvothermal conditions, formulated as [Co(L)(DMF)] (1), [Co(L)(H₂O)]·DMF (2), [Co₃(L)₂(HCOO)₂(H₂O)₂] (3), [Co₅(L)₄(OH)₂(H₂O)₂]·0.5DMF·H₂O (4), [Mn(L)(H₂O)]·DMF (5), and [Zn(L)]·DMF (6) (DMF = N,N-dimethylformamide). Complex 1 exhibits a 2D layer structure with a four-connected net. 2 is also a 2D layer net which forms a 2D stacked layers porous framework through hydrogen bonding interactions. In 3, 10-connected clusters [Co₃(COO)₆] are extended by a L²⁻ linker to construct a 3D (3,10)-connected framework with a (4·6·8)(4²·6²·8¹⁰·10) topology net. As for 4, a rare pentanuclear cluster, [Co₅(μ₃-OH)₂(COO)₈N₄], serves as a 12-connected node to give a 3D (3,12)-connected framework with a larger solvent accessible volume. 5 shows a 2D 4⁴ layer framework by considering Mn(II) as a four-connected node. 6 exhibits a 3D framework based on 1D Zn–(COO)–Zn chains. All complexes have been characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental analysis, thermogravimetric analysis and powder X-ray diffraction measurements. The magnetic properties of complexes 1–5 and the photoluminescence properties for 6 have been investigated. H₂, N₂ and CO₂ adsorption measurements were carried out for 4.