Enhanced gas sorption and breathing properties of the new sulfone functionalized COMOC-2 metal organic framework

Abstract

A new sulfone functionalized vanadium metal–organic framework (MOF), denoted as SO₂-COMOC-2, has been synthesized solvothermally. Its structural and gas sorption properties towards CO₂ and CH₄ have been evaluated and compared to those of the pristine COMOC-2 material. The SO₂-COMOC-2 shows a remarkable increase in CO₂ capacity at ambient pressure (2.13 mmol g⁻¹ at 273 K vs. 1.23 mmol g⁻¹ for the pristine COMOC-2). Additionally, the high pressure CO₂ sorption isotherm shows a distinctive two-step sorption behavior with a final capacity of 12.45 mmol g⁻¹ for SO₂-COMOC-2 at 303 K, while for CH₄ a typical Type I isotherm was obtained with a capacity of 4.13 mmol g⁻¹. In situ synchrotron X-ray powder diffraction measurements have been carried out to characterize the structural flexibility of the materials, showing both the presence of large pore and narrow pore form. Furthermore, synchrotron XANES and a variety of spectroscopic techniques have been utilized to verify the presence of hydroxyl groups and the existence of the mixed vanadium oxidation states in the titled MOF structure.