Fuelpurification, Lewis acid and aerobic oxidation catalysis performed by a microporous Co-BTT (BTT3− = 1,3,5-benzenetristetrazolate) framework having coordinatively unsaturated sites

Abstract

Two isostructural microporous metal–organic frameworks [Co(DMA)₆]₃[(Co₄Cl)₃(BTT)₈(H₂O)₁₂]₂·12H₂O (BTT³⁻ = 1,3,5-benzenetristetrazolate; DMA = N,N′-dimethylacetamide) (1) and [Cd(DMF)₆]₃[(Cd₄Cl)₃(BTT)₈(H₂O)₁₂]₂·14H₂O·4DMF (DMF = N,N′-dimethylformamide) (2) were synthesized under solvothermal conditions. The structures of both compounds were determined by single-crystal X-ray diffraction data. Each compound adopts a porous three-dimensional framework consisting of square-planar [M₄Cl]⁷⁺ (M²⁺ = Co, 1; Cd, 2) units interconnected by triangular tritopic BTT³⁻ bridging ligands to give an anionic (3,8)-connected “Moravia” net. Phase purity of the compounds was confirmed by X-ray powder diffraction (XRPD), IR spectroscopy, thermogravimetric (TG) and elemental analysis. TGA and temperature-dependent XRPD (TDXRPD) experiments indicate a moderate thermal stability up to 350 and 300 °C, respectively. Guest exchange followed by heating led to microporous solids with coordinatively unsaturated metal sites. These unsaturated metal sites create opportunities in adsorptive and catalytic applications. These have been probed by the selective removal of sulfur compounds from fuel feeds as well as the catalytic ring opening of styrene oxide and the oxidation of several cycloalkanes and benzyl compounds.