A one-dimensional coordination polymer of 5-[(imidazol-1-yl)methyl]benzene-1,3-dicarb­oxy­lic acid with Cu^II cations

5-[(Imidazol-1-yl)methyl]benzene-1,3-dicarb­oxy­lic acid (H₂L) was synthesized and the dimethyl­formamide- and dimethyl­acetamide-solvated structures of its adducts with Cu^II, namely catena-poly[[copper(II)-bis­[μ-3-carb­oxy-5-[(imidazol-1-yl)methyl]benzoato]] di­methyl­form­amide disolvate], {[Cu(C₁₂H₉N₂O₄)₂]·2C₃H₇NO}_n, (I), and catena-poly[[copper(II)-bis­[μ-3-carb­oxy-5-[(imid­azol-1-yl)methyl]benzoato]] dimethyl­acet­amide disolvate], {[Cu(C₁₂H₉N₂O₄)₂]·2C₄H₉NO}_n, (II), the formation of which are associated with mono-deprotonation of H₂L. The two structures are isomorphous and isometric. They consist of one-dimensional coordination polymers of the organic ligand with Cu^II in a 2:1 ratio, [Cu(μ-HL)₂]_n, crystallizing as the dimethyl­formamide (DMF) or dimethyl­acetamide (DMA) disolvates. The Cu^II cations are characterized by a coordination number of six, being located on centres of crystallographic inversion. In the polymeric chains, each Cu^II cation is linked to four neighbouring HL⁻ ligands, and the organic ligand is coordinated via Cu—O and Cu—N bonds to two Cu^II cations. In the corresponding crystal structures of (I) and (II), the coordination chains, aligned parallel to the c axis, are further inter­linked by strong hydrogen bonds between the noncoordinated carb­oxy groups in one array and the coordinated carboxyl­ate groups of neighbouring chains. Mol­ecules of DMF and DMA (disordered) are accommodated at the inter­face between adjacent polymeric assemblies. This report provides the first structural evidence for the formation of coordination polymers with H₂L via multiple metal–ligand bonds through both carboxyl­ate and imidazole groups.