Role of Metal–Organic Framework Topology on Thermodynamics of Polyoxometalate Encapsulation

• DOI: 10.1021/acsami.4c05016
• Publication Date: 2024-06-03T04:38:52Z
• Authors: Kira M. Fahy; Fanrui Sha; Susanne Reischauer; Seryeong Lee; Tzu-Yi Tai; Omar K. Farha

Polyoxometalates (POMs) are discrete anionic clusters whose rich redox properties, strong Bro̷nsted acidity, and high availability of active sites make them potent catalysts for oxidation reactions. Metal-organic frameworks (MOFs) have emerged as tunable, porous platforms to immobilize POMs, thus increasing their solution stability and catalytic activity. While POM@MOF composite materials have been widely used for a variety of applications, little is known about the thermodynamics of the encapsulation process. Here, we utilize an up-and-coming technique in the field of heterogeneous materials, isothermal titration calorimetry (ITC), to obtain full thermodynamic profiles (ΔH, ΔS, ΔG, and Ka) of POM binding. Six different 8-connected hexanuclear Zr-MOFs were investigated to determine the impact of MOF topology (csq, scu, and the) on POM encapsulation thermodynamics.