Poly[hexa­aqua­hexa­kis­(μ-pyridine-2,4-dicarboxyl­ato)tricopper(II)dieuropium(III)]

The asymmetric unit of the title heterometallic coordination polymer, [Cu(3)Eu(2)(C(7)H(3)NO(4))(6)(H(2)O)(6)](n), contains one Eu(III) and two Cu(II) atoms, three pyridine-2,4-dicarboxylate (pdc)(2-) anions and three water molecules. One Cu(II) atom is located on an inversion center and is N,O-chelated by two pdc(2-) anions in the equatorial plane and further coordinated by two carboxyl-ate O atoms from another two pdc anions in the axial positions, with an elongated octa-hedral geometry [Cu-O = 2.409 (3) Å in the axial direction]; the other Cu atom is N,O-chelated by two pdc anions in the coordination basal plane and coordinated by a carboxyl O atom at the apical position with a distorted square-pyramidal geometry [Cu-O = 2.359 (3) Å in the apical direction]. The Eu atom is eight-coordinated with a distorted square-anti-prismatic geometry formed by five carboxyl-ate O atoms from five pdc anions and three water mol-ecules. The carboxyl-ate anions bridge adjacent Eu and Cu atoms, forming the coordination polymer. Inter- and intra-molecular O-H⋯O hydrogen bonding occurs in the structure. π-π stacking further consolidates the crystal structure, the centroid-centroid distance between parallel pyridine rings being 3.367 (2) Å.