Innovative application of metal-organic frameworks for encapsulation and controlled release of allyl isothiocyanate

• MOFs surface area and structural features affect their AITC loading capacity.
• Cage-like pores and interpenetrating framework of MOFs influence AITC adsorption.
• Release of AITC from MOFs is controlled by the concentration of relative humidity.
• High RH could act as an external stimulus to trigger AITC release from these MOFs.
• High RH induces AITC release through two different proposed mechanisms.

This research investigated the technical feasibility of metal-organic frameworks (MOFs) as novel delivery systems for encapsulation and controlled release of volatile allyl isothiocyanate (AITC) molecules. We hypothesized that water vapor molecules could act as an external stimulus to trigger the release of AITC molecules encapsulated in MOFs. To test this hypothesis, three MOFs—HKUST-1, MOF-74(Zn), and RPM6-Zn—were selected based on their structural properties and AITC molecular characteristics. Results from adsorption-desorption and GC headspace analyses showed that these MOFs could encapsulate and retain AITC molecules within their pores under low (30–35%) relative humidity (RH) conditions. In contrast, the release of AITC molecules from all these MOFs was triggered under high RH (95–100%) conditions. These findings along with results from SEM, TEM, and XRPD studies support our hypothesis that water vapors could trigger the AITC release from these MOFs, indicating that development of the AITC-MOFs delivering system is technically feasible.