In situ NMR and DFT modeling demonstrate that N,N-dimethylformamide (DMF) promotes the formation of metal–organic framework NH2–MIL-101(Al). In situ NMR studies show that upon dissociation of an aluminum-coordinated aqua ligand in NH2–MOF-235(Al), DMF forms a H–Cl–DMF complex during synthesis. This reaction induces a transformation from the MOF-235 topology into the MIL-101 topology. Electronic structure density functional theory (DFT) calculations show that the use of DMF instead of water as the synthesis solvent decreases the energy gap between the kinetically favored MIL-101 and thermodynamically favored MIL-53 products. DMF therefore promotes MIL-101 topology both kinetically and thermodynamically.