The proponent’s discovery of ultrafast molecular rotors (Perego et al., Nat. Chem. 2020) that retain dynamics down to 2 K opened the way to exploring such rotors in more densely packed MOF architectures. We incorporated ultrafast rotors into increasingly complex frameworks while preserving mobility. We demonstrated cascade dynamics in layered pillared MOFs (Perego et al., JACS 2021) and introduced dipolar CF₂ rotors, achieving correlated dipole reorientation at 17 cal/mol, modulated by CO₂ sorption, thus yielding responsive ferroelectric behaviour (Perego et al., Angew. Chem. Int. Ed. 2023). The present work extends this family to “framework-swelling” flexible layered MOFs containing apolar and dipolar rotors. High-resolution synchrotron PXRD under controlled atmospheres and low temperatures is essential to resolve structural phase transitions, conformational changes, and unit-cell evolution, and to map the structure–temperature–mobility landscape underlying ultrafast rotor dynamics.