Exploring 5-fluoronicotinic acid as a versatile building block for the generation of topologically diverse metal–organic and supramolecular Ni, Co, and Cd networks

Abstract

Five new coordination compounds, namely [Ni(5-Fnic)₂(μ₂-H₂O)_0.5]_n (1), [Co(5-Fnic)₂(H₂biim)]_n (2), {[Cd(5-Fnic)₂(phen)]·2H₂O}_n (3), [Cd(5-Fnic)₂(H₂biim)₂] (4), and [Co(5-Fnic)₂(H₂O)₄] (5), were generated by hydrothermal methods from the metal(II) nitrates, 5-fluoronicotinic acid (5-FnicH), and an optional ancillary 1,10-phenanthroline (phen) or 2,2′-biimidazole (H₂biim) ligand. All the products 1–5 were characterized by IR spectroscopy, elemental, thermogravimetric, and single-crystal X-ray diffraction analyses. Their structures range from the intricate 3D metal–organic framework (MOF) 1 to the 1D coordination polymers 2 and 3, and the discrete 0D monomers 4 and 5. The structures of 2–5 are further extended [1D → 2D (2), 1D → 1D (3), 0D → 1D (4), and 0D → 3D (5)] into various H-bonded networks. The topological analysis of the underlying coordination (in 1) and H-bonded (in 2–5) nets revealed a very rare 3,6T10 MOF topology in 1, a parallel 2D + 2D interpenetration of the sql nets in 2, a topologically unique double chain in 3, a simple 2C1 topology in 4, and a pcu (alpha-Po primitive cubic) topology in 5. The magnetic (for 1 and 2) and luminescent (for 3 and 4) properties were also investigated and discussed.