Poly[[tetra-aqua-tetra-kis-[μ(3)-5-(pyridine-4-carboxamido)-isophthalato]-cobalt(II)-diholmium(III)] tetra-hydrate].

In the centrosymmetric polymeric title compound, {[CoHo(2)(C(14)H(8)N(2)O(5))(4)(H(2)O)(4)]·4H(2)O}(n), the Ho(III) ion is coordinated by one water mol-ecule and four 5-(pyridine-4-carboxamido)-isophthalate (L) ligands in a distorted square-anti-prismatic arrangement. The Co(II) ion, located on an inversion center, is coordinated by two pyridine N atoms, two carboxyl-ate O atoms and two water mol-ecules in a distorted octa-hedral geometry. One L ligand bridges two Ho ions and one Co ion through two carboxyl-ate groups and one pyridine N atom. The other L ligand bridges two Ho ions and one Co ion through two carboxyl-ate groups, while the uncoordinated pyridine N atom accepts a hydrogen bond from an adjacent coordinated water mol-ecule. Extensive O-H⋯O, N-H⋯O and O-H⋯N hydrogen bonding is present in the crystal.