Synthesis and structural determination of new multidimensional coordination polymers with 4,4′-oxybis(benzoate) building ligands: Construction of coordination polymers with heteroorganic bridges

We report on the synthesis and crystal structures of two new zinc coordination polymers with 4,4′-oxybis(benzoate) (oba) ligands. Single crystals of [Zn2(oba)2(azpy)(dmf)2] · 6DMF(azpy = 4,4′-azopyridine) and [Zn2(oba)2(bpe)] · 2DMF · 4H2O (bpe = trans-1,2-bis(4-pyridyl)ethylene) were prepared by treatment of Zn(CH3COO)2 · 2H2O with the H2oba and bis-pyridine type ligands, azpy and bpe, respectively, in DMF. Compound [Zn2(oba)2(azpy)(dmf)2] · 6DMF has a unique ladder structure comprising of heteroorganic bridges, in which the Zn–oba chains construct the side rails, while the Zn–azpy–Zn parts construct the rungs of the ladder framework. Despite the large size of the cavities, these ladder chains stack without interpenetration, and the cavities in the ladder framework are partially connected to create one-dimensional channel-like cavities. Compound [Zn2(oba)2(bpe)] · 2DMF · 4H2O exhibits a three-dimensional coordination framework that is comprised of heteroorganic bridges. The framework is interwoven by two-dimensional layers of [Zn2(oba)2] and the Zn2–bpe chains. The three-dimensional framework, which contains large cavities, about 13 × 11 Å2 in area, has a high porosity and a density of only 0.53 g cm−3.