A three-dimensional zinc-based coordination polymer built from 5-carboxyl­ato-1-carboxyl­atomethyl-2-oxidopyridinium with a 4-connected sra topology

In a novel three-dimensional Zn^II coordination polymer prepared by the hydro­thermal assembly of Zn(CH₃COO)₂·2H₂O and 5-carb­oxy-1-(carb­oxy­methyl)pyridin-1-ium-2-olate (H₂ccop), the Zn^II atom adopts a five-coordinated distorted trigonal biyramidal geometry. The ccop²⁻ ligands adopt the same μ₄-bridging mode linking four Zn^II cations and giving rise to a three-dimensional framework with a 4-connected sra topology.