pH-Controlled Assembly of 3D and 2D Zinc-Based Metal-Organic Frameworks with Tetrazole Ligands

We report the synthesis and structural diversity of Zn(II) metal-organic framework (MOF) with in situ formation of tetrazole ligand 3-ptz [3-ptz = 5-(3-pyridyl) tetrazolate] as a function pH. By varying the initial reaction pH, we obtain highquality crystals of the noncentrosymmetric three-dimensional MOF Zn(3-ptz)(2), mixed phases involving the zinc-aqua complex [Zn(H2O)(4)(3-ptz)(2)]center dot 4H(2)O, and two-dimensional MOF crystals Zn(OH)(3-ptz) with a tunable microrod morphology, keeping reaction time, temperature, and metal-ligand molar ratio constant. Structures are characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and UV-vis spectroscopy. We discuss the observed structural diversity in terms of the relative abundance of hydroxo-zinc species in solution for different values of pH.