Synthesis, structure and hydrogen adsorption of a novel porous metal–organic framework, Mn9(btt)2(HCOO)12·0.7DMF·0.9H2O, where btt = 1,3,5-benzenetristetrazolate

Abstract

A novel porous metal–organic framework, Mn₉(btt)₂(HCOO)₁₂·0.7DMF·0.9H₂O, was synthesized solvothermally in mixed H₂O–DMF. Its structure was characterized by single-crystal X-ray diffraction techniques, which reveal that it is constructed by cross-linking Mn²⁺ ions with 1,3,5-benzenetristetrazolates and formates, which formed in situ from the hydrolysis of dimethylformamide, to form a 3D framework with parallel hexagonal channels. Although the Mn²⁺ ions at 4f Wyckoff sites are 75% occupied, the framework remains robust and porous upon evacuation of solvent molecules, with 264 m²g⁻¹ BET surface area and hydrogen adsorption capacity of ca. 0.9 wt% at 77 K and 1 atm. Photoluminescence studies exhibit a blue band with λ_max = 418 nm.