Topological Diversification in Metal-Organic Frameworks: Secondary Ligand and Metal Effects

A series of interesting coordination polymers have been prepared by the combination of a V-shaped 4,4'-oxybis(benzoic acid) (H(2)oba) and neutral organonitrogen ligands with different metal ions, namely, {[M(oba)(bpe)center dot H2O}(n) [M = Mn (1), Co (2)], [M(oba)(N3)](n) [N3 = dipyridin-2-ylamine; M = Cd (3), Cu (4)] and {[Zn(oba)(N5)center dot 2H(2)O)(n) (5) [bpe = 1,2-bis(4-pyridyl)ethene, N5 = bis(pyridin-2-yl)pyridine-2,6-diamine]. The framework structures of these neutral polymeric complexes have been determined by single-crystal X-ray diffraction studies. Compound I has a threefold pcu-type network structure. Although 2 has the same ligands and coordination modes as 1, it consists of corrugated 2D layers formed of a series of squares, which allows the sheets to interpenetrate in an unusual 2D -> 3D parallel fashion. Polymers 3 and 4 exhibit double-helical chains formed by pi-pi stacking interactions from the phenyl rings of the N3 ligands. Compound 5 forms a 2D supramolecular architecture directed by hydrogen bonding between the NH groups of the N5 ligand, the uncoordinated carboxylate oxygens, and the intercalated water molecules, This work markedly indicates that the effect of auxiliary ligands is significant in the construction of these network structures, which are also well regulated by the metal centers. Thermogravimetric analysis (TGA) and XRPD results for compound 1 as well as luminescent properties for compounds 3 and 5 are discussed. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)