catena-Poly[[tri­aqua­copper(II)]-μ-5-carb­oxy­benzene-1,3-di­carboxyl­ato-κ²O¹:O³]

In the title complex, [Cu(C₉H₄O₆)(H₂O)₃]_n, the Cu^II cation exhibits a distorted square-pyramidal coordination geometry involving five O atoms from two monodentate 5-carb­oxy­benzene-1,3-di­carboxyl­ate anions and three water mol­ecules. The 5-carb­oxy­benzene-1,3-di­carboxyl­ate anions bridge Cu^II cations into zigzag polymeric chains running along the b-axis direction. These chains are further linked by O—H...O hydrogen bonds between coordinating water mol­ecules or carboxyl groups and carboxylate groups into a three-dimensional supra­molecular architecture. In the crystal, π–π stacking is observed between parallel benzene rings of adjacent chains, the centroid–centroid distances being 3.584 (3) and 3.684 (3) Å.

Poly[di-μ₉-citrato-tetra­sodiumzinc]

In the title compound, [Na₄Zn(C₆H₅O₇)₂]_n, the Zn^II ion lies on an inversion center and is coordinated by six O atoms from two citrate ligands, forming a distorted octa­hedral geometry. There are two crystallographically independent Na⁺ cations in the asymmetric unit. One Na⁺ cation exhibits a distorted square-pyramidal geometry defined by five O atoms from four citrate ligands. The other Na⁺ cation is surrounded by six O atoms from five citrate ligands in a distorted octa­hedral geometry. The Na⁺ cations are bridged by citrate carboxyl­ate groups, forming a layer parallel to (100). The layers are further assembled into a three-dimensional network with the [Zn(citrate)₂]⁴⁻ building units as `pillars'; O—H...O hydrogen bonds also stabilize the structure.