Anionic Gallium-Based Metal−Organic Framework and Its Sorption and Ion-Exchange Properties

A gallium-based metal−organic framework Ga6(C9H3O6)8·(C2H8N)6(C3H7NO)3(H2O)26 [1, Ga6(1,3,5-BTC)8·6DMA·3DMF·26H2O], GaMOF-1; BTC = benzenetricarboxylate/trimesic acid and DMA = dimethylamine], with space group I4̅3d, a = 19.611(1) Å, and V = 7953.4(6) Å3, was synthesized using solvothermal techniques and characterized by synchrotron-based X-ray microcrystal diffraction. Compound 1 contains isolated gallium tetrahedra connected by the organic linker (BTC) forming a 3,4-connected anionic porous network. Disordered positively charged ions and solvent molecules are present in the pore, compensating for the negative charge of the framework. These positively charged molecules could be exchanged with alkali-metal ions, as is evident by an ICP-MS study. The H2 storage capacity of the parent framework is moderate with a H2 storage capacity of ∼0.5 wt % at 77 K and 1 atm.