Green Reconstruction of MIL-100 (Fe) in Water for High Crystallinity and Enhanced Guest Encapsulation

MIL-100 (Fe) is a highly porous metal–organic framework (MOF), considered as a promising carrier for drug delivery and for gas separation and capture applications. However, this functional material suffers from toxic synthesis that may hinder its biomedical use and large-scale production for commercial applications. Herein, we report a “green” mechanochemical water immersion approach to yield highly crystalline MIL-100 (Fe) material. Subsequently, we have harnessed this strategy for facile fabrication of drug@MOF composite systems, comprising (guests) 5-fluorouracil, caffeine, or aspirin encapsulated in the pores of (host) MIL-100 (Fe). Inelastic neutron scattering was uniquely used to probe the guest–host interactions arising from pore confinement of the drug molecules, giving additional insights into the reconstruction mechanism. Our results pave the way for “green” production of MIL-type materials and bespoke guest-encapsulated composites by minimizing the use of toxic chemicals, while enhancing energy efficiency and the material’s life cycle that is central to biotechnological applications.