Encapsulation and controlled release of fragrances from functionalized porous metal-organic frameworks

In the fragrance and perfume industry, the encapsulation and controlled release of fragrance is important to appeal to consumers and promote the quality of products. Here, we demonstrate that porous metal-organic frameworks (MOFs) can effectively encapsulate and release fragrant molecules in a controlled manner. The incorporation of functional groups into MOFs can improve the adsorption and release behavior of fragrant molecules. We find that polar ester-type fragrances exhibit higher adsorption on polar hydroxyl-functionalized MOF [UiO-66-(OH)(2)] than on nonpolar MOF (UiO-66), while nonpolar terpenoid-type fragrances show no adsorption difference between these two MOFs. The release profiles show that UiO-66-(OH)(2) can prolong the release of polar fragrances compared with nonpolar fragrances. Both the experimental results and computer molecular modeling demonstrate that the hydroxyl groups in UiO-66-(OH)(2) can form strong hydrogen binding with different ester fragrances. The releasing kinetics indicates that pore diffusion is the rate-limiting step of fragrance release from MOFs. (c) 2018 American Institute of Chemical Engineers AIChE J, 65: 491-499, 2019