Synthesis and Characterization of Gamma Cyclodextrin Metal Organic Framework and Encapsulation of Ethanol

Various porous materials, including metal organic frameworks (MOFs), have been extensively researched in recent years for different applications. MOFs are synthesized by the coordination of metal ions with organic binders. Different molecules can be incorporated into the pores of MOFs. This host-guest chemistry can be used to absorb established active organic compounds. The prolonged release of such active species can be used to optimize the shelf life of food products. In this study biobased γ-cyclodextrin metal organic framework (γ-CDMOF) was synthesized using methanol diffusion in a solution of γ-CD and potassium hydroxide (KOH). γ-Cyclodextrin (γ-CD) is a symmetric oligosaccharide produced from starch that is already used as a solvent and stabilizer in various food products. Ethanol was encapsulated in the γ-CDMOF crystals using vapor diffusion. The synthesized γ-CDMOF crystals were characterized before and after encapsulation using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transformation infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The XRD pattern shows the crystallinity of the γ-CDMOF, from which a successful synthesis can be concluded. This conclusion is also confirmed by the images obtained with SEM. The TGA results show that γ-CDMOF can encapsulate ~20% ethanol. The results of DSC and FTIR show that ethanol is indeed encapsulated. Moreover, it appears that ethanol has little influence on γ-CDMOF.