The internal standard stock solution was prepared by dissolving MA (87.6 mg, 0.754 mmol) in dimethylsulfoxide (DMSO-d6, 10952.62 mg, 140.18 mmol). Since the corresponding MOF (MOF-5) is digested using D2SO4 (for qNMR purposes), we prepared the calibration curve by addition of a representative amount of D2SO4. The weighed mass of each compound can be found in Table .