Monomers, chains, ladders, and two-dimensional sheets: Structural diversity in six new compounds of Zn(II) with 4,4′-bipyridine

Six new zinc(II)–4,4′-bipyridine coordination polymers with diverse structural topologies are reported. The reaction of one equivalent of zinc(II) perchlorate hexahydrate with three equivalents of 4,4′-bipyridine (bipy) under hydrothermal conditions produces a mixture of [Zn(4,4′-bipy)2(H2O)4](ClO4)2 · 2(4,4′-bipy) (1), [Zn3(4,4′-bipy)4(OAc)4](ClO4)2 · 2(H2O) (2), and [Zn3(4,4′-bipy)3(OAc)4(H2O)2](ClO4)2 · (H2O) (3) (OAc = acetate), for which single crystals can be isolated. Compound 1 contains sheet-like arrays of discrete monomers co-crystallized with uncoordinated bipy molecules to form extended triangular channels containing counterions. Compounds 2 and 3 consist of acetate-bridged zinc trimers linked by bipy to form three-leg ladders that are isolated in 3 and further linked by bipy into two-dimensional networks in 2. The reaction of one equivalent of zinc(II) perchlorate hexahydrate with 1.5 equivalents of bipy in dimethyl sulfoxide yields single crystals of [Zn(4,4′-bipy)(ClO4)(H2O)(OH)] (4) and [Zn(4,4′-bipy)(DMSO)4](ClO4)2 (5) while crystals of [Zn(4,4′-bipy)3(DMSO)2](ClO4)2] · 2(4,4′-bipy) · (H2O) (6) are obtained from DMSO with three equivalents of bipy. Compound 4 is a mutually interpenetrated network of hydrogen-bonded, one-dimensional Zn–bipy zig-zag chains and compound 5 exists as isolated, linear chains. Compound 6 also contains linear chains, linked in three-dimensions by π-stacking interactions between bipy ligands and guests.

Graphical abstractSix new zinc(II)–4,4′-bipyridine coordination polymers with diverse structural topologies are reported. The versatility of bipy as a spacer ligand when assembling transition metal ions into coordination polymers is illustrated, providing examples of monomeric, linear chain, zig-zag chain, ladder, and two-dimensional network structures.Figure optionsDownload full-size imageDownload as PowerPoint slide