A twofold interpenetrating three-dimensional zinc-organic framework built from naphthalene-1,4-dicarboxylate and 4,4'-bipyridine ligands.

A novel three-dimensional Zn(II) complex, poly[[(μ2-4,4'-bipyridine)(μ4-naphthalene-1,4-dicarboxylato)(μ2-naphthalene-1,4-dicarboxylato)dizinc(II)] dimethylformamide monosolvate monohydrate], {[Zn2(C12H6O4)2(C10H8N2)]·2C3H7NO·H2O)}n, has been prepared by the solvothermal assembly of Zn(NO3)·6H2O, naphthalene-1,4-dicarboxylic acid and 4,4'-bipyridine. The two crystallographically independent Zn atoms adopt the same four-coordinated tetrahedral geometry (ZnO3N) by bonding to three O atoms from three different naphthalene-1,4-dicarboxylate (1,4-ndc) ligands and one N atom from a 4,4'-bipyridine (bpy) ligand. The supramolecular secondary building unit (SBU) is a distorted paddle-wheel-like {Zn2(COO)2N2O2} unit and these units are linked by 1,4-ndc ligands within the layer to form a two-dimensional net parallel to the ab plane, which is further connected by bpy ligands to form the three-dimensional framework. The single net leaves voids that are filled by mutual interpenetration of an independent equivalent framework in a twofold interpenetrating architecture. The title compound is stable up to 673 K. Excitation and luminescence data observed at room temperature show that it emits bright-blue fluorescence.