Exceptionally stable, hollow tubular metal-organic architectures: Synthesis, characterization, and solid-state transformation study

An effective solvothermal procedure has been developed to synthesize the new three-dimensional metal-organic framework, [Zn F(AmTAZ)] .solvents, using either 3-amino-1,2,4-triazole (AmTAZ) or 3-amino1,2,4-triazole-5-carboxylic acid (AmTAZAc) and a choice of several Zn(II) salts as starting materials. The three-dimensional structure displays open-ended, hollow nanotubular channels that are formed by hexanuclear metallamacrocyclic Zn6F6(AmTAZ)(6) rings. The framework integrity is maintained to 350 degreesC, at which point most of the guest solvent molecules have been removed, as evidenced by single-crystal X-ray analyses, H-1 solid-state NMR, and TGA measurements. At higher temperatures, the framework is converted either to zinc oxide (ZnO) when heated in air or to zinc cyanamide (ZnCN2) when heated in an inert atmosphere. In both cases, the as-grown, rodlike crystal shape is maintained during the solid-state transformation, suggesting a possible route for preparing one-dimensional crystalline nanornaterials.