A series of mixed-ligand 2D and 3D coordination polymers assembled from a novel multifunctional pyridine-tricarboxylate building block: hydrothermal syntheses, structural and topological diversity, and magnetic and luminescent properties

Abstract

A series of novel mixed-ligand coordination polymers, namely, {[Cd₂(μ₄-L)(μ₃-OH)(phen)₂]·2H₂O}_n (1), {[Mn₃(μ₅-L)₂(phen)₂(H₂O)]·H₂O}_n (2), [Cd₂(μ₃-L)(H₂biim)₂(μ₂-Hbiim)]_n (3), {[Pb₂(μ₄-L)(μ₄-bpdc)_0.5(phen)₂]·H₂O}_n (4), [Cd₂(μ₅-L)(μ₂-bpdc)_0.5(phen)₂]_n (5), and [Zn₂(μ₄-L)(μ₂-bpdc)_0.5(py)₂]_n (6), was hydrothermally synthesized using 4-(5-carboxypyridin-2-yl)isophthalic acid (H₃L) as a new and virtually unexplored multifunctional pyridine-tricarboxylate building block, along with various auxiliary ligands {phen = 1,10-phenanthroline, H₂biim = 2,2′-biimidazole, H₂bpdc = 4,4′-biphenyldicarboxylic acid, and py = pyridine}. All the products 1–6 were characterized by IR spectroscopy, elemental, thermogravimetric, and single-crystal X-ray diffraction analyses. Compounds 1, 3, and 5 reveal 2D metal–organic layers with the kgd, fes, and 3,4,5L5 topology, respectively, whereas the metal–organic frameworks (MOFs) 2, 4, and 6 disclose 3D underlying nets with the unique (2, 4) or ins (6) topology. The results indicate that the nature of the metal(II) ion and type of auxiliary ligand play a significant role in determining the dimensionality, topology and other structural features of the obtained products. Luminescent (for 1 and 3–6) and magnetic (for 2) properties were studied and discussed.