Direct One-pot Synthesis of Highly Tunable Mixed-linker UiO-66-(SH)2 Metal-Organic Frameworks: Enroute Toward Robust Sulfonic Acid Tagged UiO-66 Architectures

Abstract

Synthesis, storage, and characterization of thiol functionalized metal-organic frameworks (MOFs) is highly challenging. However, they continue to be of great interest due to their broad spectrum of applications. In this work, for the first time, a solid solution approach has been adopted to dilute the thiol content in UiO-66-(SH)2 [Universitetet i Oslo] MOF by terephthalic acid linker without influencing its topology. Detailed characterization of the mixed-linker UiO-66-(SH)2 MOF samples have been performed using powder X-ray diffraction (PXRD), N2 sorption, X-ray photoelectron spectroscopy (XPS) and electron microscopy. The solid dilution had an overall impact on the crystallinity, defects, porosity and particle size of the UiO-66-(SH)2 framework. This study has the potential to significantly influence the syntheses of nanoscale thiol functionalized MOF materials and their applications in photocatalysis, water purification and drug delivery. This work also incorporates post synthetic oxidation (PSO) to produce sulfonic acid tagged mixed-linker UiO-66 frameworks. The solid dilution has been found to be critical in preventing the frameworks from losing their crystallinity and porosity, upon activation. Thus, this work also paves the way for a general strategy to impart stability to sulfonic acid tagged UiO-66 framework having wide ranging applications.