Structure–kinetics relationships in β-cyclodextrin metal–organic frameworks for selective volatile bioactive delivery

The selective adsorption and controlled release of volatile bioactive compounds is of broad interest for applications in active packaging, fragrance stabilization, and therapeutic delivery. In this study, ß-cyclodextrin-based metal–organic frameworks (ß-CD MOFs) were synthesized via a methanol vapor diffusion method using potassium ions as coordination nodes, yielding well-defined cuboidal microcrystals with uniform aspect ratios. Comprehensive characterization using scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), and proton nuclear magnetic resonance (1H NMR) confirmed the formation of a highly crystalline, thermally stable MOF capable of encapsulating structurally distinct volatile guests, including eugenol, cinnamon essential oil, and oregano essential oil. Adsorption kinetics indicated compound-specific host–guest interactions, with eugenol and cinnamon oil exhibiting interaction-influenced uptake behavior, while oregano oil showed diffusion-dominated adsorption. Release studies demonstrated predominantly sustained release profiles that were well described by zero-order and Higuchi diffusion models; notably, eugenol displayed a biphasic release characterized by an initial burst followed by prolonged zero-order release. These findings demonstrate the tunability of ß-CD MOFs as a sustainable carbohydrate-based platform for selective and programmable volatile delivery across diverse application domains.