UiO-66 is one of the most chemically stable metal–organic frameworks(MOFs)available.However,little is known about its stability in organic solvents.In this study,we synthesized a highly defective UiO-66(HD-UiO-66)and...UiO-66 is one of the most chemically stable metal–organic frameworks(MOFs)available.However,little is known about its stability in organic solvents.In this study,we synthesized a highly defective UiO-66(HD-UiO-66)and a less defective one(D-UiO-66)and explored how their properties change when exposed to weak and strong acids,both organic and inorganic,and dissolved in different solvents:water,dichloromethane(DCM),and tetrahydrofuran(THF).Exposing both defective UiO-66 materials to weak acids and bases,such as acetic acid and triethylamine,maintains their crystalline structure and porosity,irrespective of the solvent.Sulphuric acid decomposes D-UiO-66 in all solvents studied and HD-UiO-66 in DCM and THF,but not in water.Trifluoroacetic acid decomposes the frameworks only in DCM.Tetramethylguanidine decomposes HD-UiO-66 and D-UiO-66 in organic solvents but maintains some of the MOFs’porosity and crystalline structure in water,whereas potassium carbonate damages the MOFs to a greater extent in water than in organic solvents.Our results show that the acid/base properties of the solvent modulate the strength of acids and bases and its polarity determines the extent of their solvation,thus playing a crucial role in altering the MOF’s textural properties.This systematic investigation highlights the central role played by the solvent in tuning the properties of MOFs,which is relevant for liquid-phase applications in acidic and basic environments,such as catalysis and adsorption.展开更多
文摘UiO-66 is one of the most chemically stable metal–organic frameworks(MOFs)available.However,little is known about its stability in organic solvents.In this study,we synthesized a highly defective UiO-66(HD-UiO-66)and a less defective one(D-UiO-66)and explored how their properties change when exposed to weak and strong acids,both organic and inorganic,and dissolved in different solvents:water,dichloromethane(DCM),and tetrahydrofuran(THF).Exposing both defective UiO-66 materials to weak acids and bases,such as acetic acid and triethylamine,maintains their crystalline structure and porosity,irrespective of the solvent.Sulphuric acid decomposes D-UiO-66 in all solvents studied and HD-UiO-66 in DCM and THF,but not in water.Trifluoroacetic acid decomposes the frameworks only in DCM.Tetramethylguanidine decomposes HD-UiO-66 and D-UiO-66 in organic solvents but maintains some of the MOFs’porosity and crystalline structure in water,whereas potassium carbonate damages the MOFs to a greater extent in water than in organic solvents.Our results show that the acid/base properties of the solvent modulate the strength of acids and bases and its polarity determines the extent of their solvation,thus playing a crucial role in altering the MOF’s textural properties.This systematic investigation highlights the central role played by the solvent in tuning the properties of MOFs,which is relevant for liquid-phase applications in acidic and basic environments,such as catalysis and adsorption.
