Initial solvothermal syntheses of highly crystalline samples of 1 were completed using scandium nitrate and fumaric acid in N,N-dimethylformamide (DMF), with ten equivalents of hydrochloric acid (HCl) as a modulator (SI, Section S2). Highly crystalline powders and single crystals of 1 were reliably produced under these conditions at 100 °C for 24 hours; the single crystal structure of 1 (Figure ), with formula [Sc3O(C4H2O4)3(H2O)2(OH)], was consistent with that reported by Wang et al. during the course of our study, from crystals prepared under different reaction conditions. Once cooled to room temperature, the materials were washed with fresh DMF three times before powder X-ray diffraction (PXRD) measurements were collected, and further solvent exchange was carried out where mentioned. The PXRD pattern collected of a sample in DMF, herein known as 1as (as-synthesised) matches closely with the calculated pattern from our single crystal structure, indicating the phasepurity of the sample. SEM imaging provides further evidence of the identity of the sample (Figure ) where 1as has a hexagonal rod-like morphology, consistent with reported MIL-88-type frameworks. The flexibility of the iron analogue MIL-88A(Fe) is well-reported, but was not detailed in the recent report of MIL-88A(Sc), and so, initially, attempts were made to collect single crystal structures of samples of 1as that were allowed to slowly dry in air (SI, Section S3). Unfortunately, crystal degradation meant only two reliable sets of unit cell parameters could be collected, which showed small but appreciable contractions in unit cell volume on loss of DMF solvent (V = 1700(3) and 1840.6(7) Å 3 , respectively) compared to 1as (V = 2073.8(11) Å 3 ), while maintaining the P63/m space group of the parent MOF. Comparison to the previously reported closed structure of MIL-88A(Fe), which has V = 1135 Å 3 , confirms that neither sample is fully closed. PXRD measurements were therefore carried out on bulk samples of 1as whilst they dried directly from DMF at room temperature in air (Figure ). 1as again contracts as residual DMF diffuses out of the pores, leading to a continuous shift of the Bragg peaks to higher 2θ angles with concomitant broadening that makes indexing the unit cell difficult. Further contraction and similar broadening of Bragg peaks are observed when 1as is dried under vacuum from DMF. Whilst it was not possible to determine the unit cell parameters of these dried samples, comparison of diffractograms with those of MIL-88A(Fe) again indicate that the sample is far from fully closed.