A joint experimental and computational systematic exploration of the driving forces that govern (i) encapsulation of active ingredients (solvent, starting material dehydration, drug/material ratio, immersion time, and several consecutive impregnations) and (i) its kinetics of delivery (structure, polarity, ...) was performed using a series of porous biocompatible metal–organic frameworks (MOFs) that bear different topologies, connectivities, and chemical compositions. The liporeductor cosmetic caffeine was selected as the active molecule. Its encapsulation is a challenge for the cosmetic industry due to its high tendency to crystallize leading to poor loadings (<5 wt %) and uncontrolled releases with a subsequent low efficiency. It was evidenced that caffeine entrapping reaches exceptional payloads up to 50 wt %, while progressive release of this cosmetic agent upon immersion in the simulated physiological media (phosphate buffer solution pH = 7.4 or distilled water pH = 6.3, 37 °C) occurred mainly depending on the degree of MOF stability, caffeine mobility, and MOF–caffeine interactions. Thus, MIL-100 and UiO-66 appear as very promising carriers for topical administration of caffeine with both spectacular cosmetic payloads and progressive releases within 24 h.

In addition to its high thermal stability, repetitive hydration/dehydration tests have revealed that the porous zirconium terephthalate UiO-66 switches reversibly between its dehydroxylated and hydroxylated versions. The structure of its dehydroxylated form has thus been elucidated by coupling molecular simulations and X-ray powder diffraction data. Infrared measurements have shown that relatively weak acid sites are available while microcalorimetry combined with Monte Carlo simulations emphasize moderate interactions between the UiO-66 surface and a wide range of guest molecules including CH(4), CO, and CO(2). These properties, in conjunction with its significant adsorption capacity, make UiO-66 of interest for its further evaluation for CO(2) recovery in industrial applications. This global approach suggests a strategy for the evaluation of metal-organic frameworks for gas-based applications.