Polyoxo-Edelmetallat-Chemie kombiniert mit metallorganischen Trägern: Eine neue Klasse heterogener Katalysatoren
Zusammenfassung der Projektergebnisse
The main focus of this work was the isolation of polyoxopalladate (POP)-based metal-organic framework (MOF) materials utilizing two strategies: (i) Strategy 1 deals with a self-immobilization process wherein the discrete and anionic POPs are organically functionalized and utilized as building blocks in the construction of porous crystalline MOFs (POP-MOFs) and (ii) Strategy 2 deals with the encapsulation of the POPs in the cavities of porous MOFs (POP@MOFs) by the solution impregnation method. The objective behind synthesizing such compounds has been to realize porous and stable heterogeneous catalysts based on POPs, which can catalyze important organic reactions heterogeneously. Utilizing Strategy 1, we have isolated the first polyoxo-noble-metalate-based MOF JUB-1, wherein a discrete cuboid POP Pd13As8 acts as a secondary building unit (SBU) and is linked by organic linkers to form a three-dimensional open framework structure that shows promise as a heterogeneous catalyst for the Suzuki-Miyaura cross-coupling reaction. This work represents the discovery of a fundamentally novel class of materials that paves the way for the full utilization of the entire class of discrete polyoxopalladates (POPs), as well as polyoxoaurates, of different shape, size, and composition, as building blocks for stable 3D framework materials. This work is on-going in our laboratory. By utilizing Strategy 2 we have isolated, for the first time, a POP-impregnated MOF material (POP@MOF), wherein the discrete cuboid-shaped, selenite-capped POP Pd13Se8 is incorporated in the pores of the preformed MOF MIL-101, leading to the composite material Pd13Se8@MIL-101. This material also acts as an efficient catalyst for Suzuki-Miyaura cross-coupling reactions under ambient conditions in aqueous solutions. The importance of this work lies in the fact that we can now potentially utilize the plethora of known discrete POPs of various sizes, shapes and compositions, as well as polyoxoaurates(III), and utilize them as guests in porous host MOFs to realize a series of functionally interesting polyoxo-noblemetalate@MOF materials. Such research works are also on-going in our laboratory.
Projektbezogene Publikationen (Auswahl)
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“Discovery of Polyoxo-Noble-Metalate-Based Metal–Organic Frameworks”, J. Am. Chem. Soc. 2019, 141, 3385
S. Bhattacharya, W. W. Ayass, D. H. Taffa, A. Schneemann, A. L. Semrau, S. Wannapaiboon, P. J. Altmann, A. Pöthig, T. Nisar, T. Balster, N. C. Burtch, V. Wagner, R. A. Fischer, M. Wark, U. Kortz
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“Polyoxopalladate-Loaded Metal–Organic Framework (POP@MOF): Synthesis and Heterogeneous Catalysis”, Inorg. Chem. 2020, 59, 10512-10521
S. Bhattacharya, W. W. Ayass, D. H. Taffa, T. Nisar, T. Balster, A. Hartwig, V. Wagner, M. Wark, U. Kortz
