Sulfate binding in zinc(II) complexes of a monopyridylurea ligand N-(1-naphthyl)-N′-(3-pyridyl)urea

Two zinc(II) complexes of a urea-functionalized pyridyl ligand, [Zn(SO4)L3]·CH3OH (1) and {[Zn(μ2-SO4)L2]·0.5CH3OH}n (2) (L = N-(1-naphthyl)-N′-(3-pyridyl)urea), have been synthesized by the reaction of L with ZnSO4·7H2O under different conditions. Complex 1 is a hydrogen-bonded 2D grid structure in which the sulfate anion not only coordinates to the ZnII ion as a monodentate ligand but also forms multiple hydrogen bonds with the urea groups of adjacent molecules. In complex 2 the sulfate ion serves as a μ2-bridging ligand, connecting the ZnII ions to form an infinite 1D organic–inorganic hybrid framework. Meanwhile, the sulfate anion is also bound by neighboring ligands through hydrogen bonds between urea groups and the non-coordinated oxygen atoms. The solid-state emission spectra of 1 and 2 show a red shift of the fluorescence emission of ligand L.