Research Projects

Polyoxometalates (POMs) are attractive compounds for host-guest chemistry because of the tunable nature of their molecular properties, such as size, shape, composition, acidity, redox potential, and solubility in aqueous and organic media. POMs are discrete, soluble, anionic metal-oxo clusters of early transition metals in high oxidation states (e.g. Mo6+, W6+, V5+), and exhibit a large range of shapes, sizes (micro- to nano-meter scale), and compositions. The unique combination of structural diversity, high thermal stability, and redox capabilities makes POMs attractive in various fields, such as magnetism, catalysis, and electronics. Besides these applications, POMs are highly effective as antibacterial, antimicrobial, antitumor, anticancer, and antidiabetic agents both in vivo and in vitro. High-nuclearity ring- or ball-shaped polyoxomolybdates have been known since 1998. Müller and coworkers pioneered the synthesis of giant polyoxomolybdates of two main structural types: the sphere or ball-shaped structures known as Keplerates (e.g. {Mo132}, {Mo102}, {Mo80V22}, {Mo72V30}, {Mo75V20}, {Mo72Fe30} and {Mo72Cr30}), and the ring-shaped structures (e.g. {Mo176}, {Mo154}, {Mo152}, {Mo146}, {Mo142}, {Mo37}, {Mo57V6}, {Mo63V6}, {Mo57Fe6}, {Mo128Eu4}2 and {Mo248}). The synthesis of metal-organic frameworks (MOFs) using POMs as linkers and/or building blocks has recently gained momentum as an effective strategy to gain access to POM-based MOFs, which merge the merits of both POMs and MOFs, for various potential applications. MOFs are a special class of crystalline organic-inorganic hybrid materials fabricated through direct self-assembly reactions between metal ions or metal-containing clusters (often called secondary building units, SBUs), and multi-dentate organic ligands, leading to frameworks with various pores. MOFs are popular materials for use in the applications of selective gas adsorption and separation, heterogeneous catalysis, proton conduction, luminescence, drug delivery, ion exchange, post-synthetic modification, ferroelectricity, and magnetism due to their tunable and dynamic porous nature, designability, and rich functionality of the organic linkers, as well as their metal-based properties. Therefore, a logical method to synthesize highly effective, stable, and recyclable POM-based materials for proton conduction, heterogeneous catalysis, and gas storage and separation applications would be to combine suitable POMs with the high internal surface areas and selective sorption properties of MOFs by synthesizing POM-based MOF materials. In this project proposal, we aim to synthesize POM ring-based MOF materials, where the rings will be used as building blocks that will result in the realization of a library of POM-based MOF materials for various potential applications, such as proton conduction, catalysis, selective CO2 adsorption, CO2 fixation, etc.