During synthetic optimisations, a new Sc-fumarate MOF named 2, with an orthorhombic unit cell (a = 17.0967( ), b = 15.1239( ), c = 12.2795( )), was discovered at higher synthesis temperatures (150 °C) with scandium nitrate and fumaric acid, again in DMF but with one equivalent of HCl as modulator (SI, Section S6). The framework has the same trigonal prismatic SBU as 1, where three scandium centres are linked by one μ3-O 2-centre and capped by carboxylate groups from the fumaric acid linkers, with the same underlying connectivity (Figures ). However, each cluster is now bridged to two others by formate anions coordinated to axial Sc positions, which replace the terminal OH anions and one of the two coordinating water ligands of 1. Only one of the three Sc 3+ ions in the SBU has axially coordinated solvent -a 1:1 ratio of occupationally disordered water and O-coordinated DMF (itself disordered over two positions) -with each water ligand hydrogen bonding to a further pore-bound DMF molecule to yield a material with overall formula [Sc3O(C4H2O4)3(HCOO)(H2O)0.5(C3H7NO)0.5]‧(C3H7NO)0.5. This formate bridging is similar to that observed by Wei et al. in rare-earth MOFs with underlying MIL-88 topologies, whereby the trinuclear SBUs are interconnected by HCOO -groups to enhance chemical and thermal stability, but these examples, with benzene-1,4-dicarboxylate and naphthalene-2,6-dicarboxylate ligands, differ in overall connectivity and coordination compared to 2. Most recently, formate bridged Sc3O trimers have been reported by Prasad et al. when synthesising Sc-BTB (BTB = benzenetribenzoate, or 1,3,5-tris(4carboxyphenyl)benzene) resulting in a chain-like SBU, rather than independent trimers. They reported that the formate groups are a direct result of the of DMF at higher temperatures in the presence of acid, similar to the synthetic conditions employed to prepare 2. Following synthesis, 2 was washed in fresh DMF three times, and subsequently by fresh acetonitrile three times, and dried under vacuum overnight before further analysis. The PXRD pattern for a bulk sample of this as-synthesised 2 closely matches the calculated pattern generated from the single crystal structure (Figure ). The 1 H NMR spectrum of a digested sample confirms the presence of formate and DMF in expected quantities, while elemental analysis and TGA further support the bulk composition matching that of the crystal structure (SI, Section S6). The TGA profile reveals that 2 is thermally stable until approximately 370 °C, where it exhibits a large mass loss relating to the decomposition of the framework. This is similar to the thermal activity exhibited by 1, however, the cleavage of the formate bridges induces a faster break down of the MOF at lower temperatures. As previously discussed, MOFs in the MIL-88 series are well-known for their flexible behaviour, however, following evacuation under vacuum at 150 °C, no changes are apparent in the powder X-ray diffractogram of 2, suggesting the formate bridges buttress the structure and do not allow it to close (Figure ). As such, 2 exhibits a type I isotherm for N2 adsorption at 77 K, with a relatively high BET surface area (SBET = 959 m 2 g -1 , Figure ), and also displays good CO2 adsorption -2.7 mmol g -1 at 1 bar at 273 K -which is comparable to other scandium MOFs (SI, Figure ). 2 also shows comparable H2 adsorption to 1np, achieving an uptake of 1.36 wt%. Incorporation of the formate bridges has imparted rigidity to 2, preventing the framework from flexing and closing, therefore eradicating the dynamic behaviour exhibited by 1.