Copper(ii) 5-methoxyisophthalate coordination polymers incorporating dipyridyl co-ligands: syntheses, crystal structures, and magnetic properties

Abstract

Hydrothermal reactions of mixed ligands 5-methoxyisophthalate (CH₃O-H₂ip) and dipyridyl with Cu(OAc)₂·2H₂O afford five new coordination polymers, including {[Cu(CH₃O-ip)(bpa)]·H₂O}_n (1), [Cu₂(CH₃O-ip)₂(bpa)_0.5(H₂O)]_n (2), [Cu₂(CH₃O-ip)₂(bpp)(H₂O)]_n (3), {[Cu₃(CH₃O-ip)₃(bpp)₂(H₂O)]·3H₂O}_n (4) and [Cu₄(CH₃O-ip)₃(bpe)(OH)₂]_n (5) (bpp = 1,3-di(4-pyridyl)propane, bpa = 1,2-bi(4-pyridyl)ethane, and bpe = 1,2-di(4-pyridyl)ethylene). Compound 1 consists of CH₃O-ip anion-bridged 1D Cu^II chains that are linked by trans-bpa into a 2D layer. Compound 2 is a 2D (4,4) layer that is connected by CH₃O-ip anions. The gauche bpa in 2 lies in the cavity and meets the coordination requirement of the paddle-wheel dimeric copper unit. Compound 3 is an extended 3D polythreading network consisting of 2D (4,4) motifs with dangling bpp lateral arms. Compound 4 exhibits a 3D (4,6)-connected self-penetrating (6⁵.8)(6¹⁴.8) network that is composed of binuclear and mononuclear metal nodes. Compound 5 exhibits a 3D network with the tetranuclear [Cu₄(μ₃-OH)₂]⁶⁺ cluster acting as nodes, which is constructed by the interconnection of 2D helical layers via bpe pillars. The results of magnetic determination show that the syn–anti carboxylato bridges in our cases induce a weak antiferromagnetic interaction in 1, and the syn–syn carboxylato bridge in 3 and 4 mediates a strong antiferromagnetic interaction.