High-Porosity Metal-Organic Framework Glasses

We report a synthetic strategy to link titanium-oxo (Ti-oxo) clusters into metal-organic framework (MOF) glasses with high porosity though the carboxylate linkage. A new series of MOF glasses was synthesized by evaporation of solution containing Ti-oxo clusters Ti₁₆ O₁₆ (OEt)₃₂ , linkers, and m-cresol. The formation of carboxylate linkages between the Ti-oxo clusters and the carboxylate linkers was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. The structural integrity of the Ti-oxo clusters within the glasses was evidenced by both X-ray absorption near edge structure (XANES) and ¹⁷ O magic-angle spinning (MAS) NMR. After ligand exchange and activation, the fumarate-linked MOF glass, termed Ti-Fum, showed a N₂ Brunauer-Emmett-Teller (BET) surface areas of 923 m²  g^-1 , nearly three times as high as the phenolate-linked MOF glass with the highest BET surface area prior to this report.