Abstract

Abstract The catalytic potential of flexible metal–organic frameworks (MOFs) remains underexplored, particularly in liquid‐phase reactions. This study employs MIL‐53(Cr), a prototypical “breathing” MOF capable of structural adaptation via pore size modulation, as a photocatalyst for the dehalogenation of aryl halides. Powder X‐ray diffraction and Pair Distribution Function analyses reveal that organic solvents influence pore opening, while substrates and products dynamically adjust the framework configuration during catalysis. This structural flexibility enables precise tuning of photocatalytic efficiency via solvent‐mediated control of the pore aperture. The results demonstrate that the dynamic behavior of MIL‐53(Cr) facilitates enhanced catalytic activity and selectivity, advancing the application of flexible MOFs as tunable, enzyme‐mimicking catalysts. These findings pave the way for the rational design of next‐generation flexible photocatalysts.