Poly[[dodecaaquabis(μ3-pyridine-2,6-dicarboxylato)tetrakis(μ2-pyridine-2,6-dicarboxylato)tricalciumdieuropium(III)] 10.5-hydrate]

In the title compound, {[Ca3Eu2(C7H3NO4)6(H2O)12]·10.5H2O}n, the EuIII ion is nine-coordinated by three tridentate pyridine-2,6-dicarboxylate (PDA) ligands, forming a [Eu(PDA)3]3− building block. The Ca2+ ions adopt two types of coordination geometries. One Ca2+ ion, lying on a twofold rotation axis, is eight-coordinated by four carboxylate O atoms from four PDA ligands and four water molecules, and the other two Ca2+ ions, each lying on an inversion center, are six-coordinated by two carboxylate O atoms from two PDA ligands and four water molecules. The carboxylate groups bridge the EuIII and Ca2+ ions into a three-dimensional porous framework, with channels extending along [010] and [001] in which lattice water molecules are located. Two of the lattice water molecules are disordered over two sets of sites with equal occupancy and one water molecule is 0.25-occupied. Numerous O—H...O hydrogen bonds involving the water molecules and carboxylate O atoms are present.