Understanding the leaching properties of heterogenized catalysts: a combined solid-state and PHIP NMR study |
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Authors: | Gutmann Torsten Ratajczyk Tomasz Xu Yeping Breitzke Hergen Grünberg Anna Dillenberger Sonja Bommerich Ute Trantzschel Thomas Bernarding Johannes Buntkowsky Gerd |
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Affiliation: | a Institute of Physical Chemistry, Technical University Darmstadt, Petersenstrasse 22, D-64287 Darmstadt, Germany;b Leibniz Institute for Neurobiology, Brenneckestraße 6, D-39118 Magdeburg, Germany;c Institute for Biometry and Medical Computer Science, Otto-von-Guericke University Magdeburg, Leipziger Straße 44, D-39120 Magdeburg, Germany |
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Abstract: | Para-hydrogen induced polarization (PHIP) NMR in solution, combined with solid-state NMR, can be efficiently employed for the highly sensitive in-situ detection of the leaching properties of immobilized catalysts. The knowledge of this property is important for possible applications of PHIP experiments in medicine, biology or industry, where leached catalysts poison the solution of hyperpolarized products. As experimental example Wilkinson's catalyst RhCl(PPh(3))(3) (1) immobilized on mesoporous silica is chosen. As model reaction the hydrogenation of styrene in solvents with different polarities (methanol-d(4), acetone-d(6) and benzene-d(6)) is used. A (31)P solid-state MAS-NMR study reveals that there are two different species of catalysts on the silica, namely coordinatively bound catalysts and physisorbed catalyst. Only the second species exhibits substantial leaching, which is visible in a strong PHIP enhancement of the reaction product. |
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Keywords: | PHIP Solid-state NMR MAS Wilkinson's catalyst Immobilization |
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