Crystal structure of a novel one-dimensional zigzag chain-like cobalt(II) coordination polymer constructed from 4,4′-bi­pyridine and 2-hy­droxy­benzoate ligands

A novel one-dimensional zigzag chain-like Co(II) coordination polymer constructed from 4,4′-bi­pyridine (4,4′-bpy) and 2-hy­droxy­benzoate (2-OHbenz) ligands, namely, catena-poly[[(4,4′-bi­pyridine-κN)­(μ-2-hy­droxy­benzoato-κ(2) O:O′)(2-hy­droxy­benzoato-κ(2) O,O′)cobalt(II)]-μ-4,4′-bi­pyridine-κ(2) N:N′-[aquahemi(μ-4,4′-bi­pyridine-κ(2) N:N′)(2-hy­droxy­benzoato-κO(2-hy­droxy­benzoato-κ(2) O:O′)cobalt(II)], [Co(2)(C(7)H(5)O(3))(4)(C(10)H(8)N(2))(2.5)(H(2)O)](n), has been synthesized by reacting cobalt(II) nitrate trihydrate, 4,4′-bpy and 2-hy­droxy­benzoic acid in a mixture of water and methanol at room temperature. There are two independent Co(II) centers, Co1 and Co2, in the asymmetric unit, revealing a distorted octa­hedral geometry with chromophore types of [CoN(2)O(4)] and [CoN(2)O(3)O′], respectively. The Co1 ions are doubly bridged by 2-OHbenz ligands with syn–anti coordination mode, generating a dinuclear unit. The bridging 4,4′-bpy ligands connect these dinuclear units and the mononuclear Co2 chromophores, providing a one-dimensional alternating zigzag chain-like structure. In the crystal, inter­molecular hydrogen bonds, C—H⋯π and π–π stacking inter­actions are observed and these help to consolidate the packing. In addition, the physical properties of the title compound are reported.