Diaqua­(5-carb­oxy­benzene-1,3-dicarboxyl­ato-κO (1))[8-ethyl-5-oxo-2-(piperazin-4-ium-1-yl)-5,8-dihydro­pyrido[2,3-d]pyrimidine-6-carboxyl­ato-κ(2) O (5),O (6)]zinc monohydrate

In the title compound, [Zn(C(14)H(17)N(5)O(3))(C(9)H(4)O(6))(H(2)O)(2)]·H(2)O, the complex mol­ecule exists in a zwitterionic form. The Zn(II) ion exhibits a distorted tetra­gonal-pyramidal geometry, being coordinated by two O atoms from the zwitterionic 8-ethyl-5-oxo-2-(piperazin-4-ium-1-yl)-5,8-dihydro­pyrido[2,3-d]pyrimidine-6-carboxyl­ate (L) ligand, one O atom from the 5-carb­oxy­benzene-1,3-dicarboxyl­ate dianion, [Hbtc](2−), and two O atoms from two aqua ligands. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds link the components into a three-dimensional structure. The crystal packing exhibits π–π inter­actions between the aromatic rings, with centroid–centroid distances in the range 3.466 (3)–3.667 (3) Å.