Formation Mechanism of a Nano-Ring of Bismuth Cations and Mono-Lacunary Keggin-Type Phosphomolybdate |
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| Authors: | Dr Inês C B Martins Dominik Al-Sabbagh Dr Ursula Bentrup Dr Julien Marquardt Dr Thomas Schmid Dr Ernesto Scoppola Werner Kraus Dr Tomasz M Stawski Dr Ana Guilherme Buzanich Dr Kirill V Yusenko Dr Steffen Weidner Dr Franziska Emmerling |
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| Institution: | 1. BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Str.11, 12489 Berlin, Germany;2. Leibniz-Institut für Katalyse e. V. (LIKAT), Albert-Einstein-Str. 29a, 18059 Rostock, Germany;3. School of Analytical Sciences Adlershof (SALSA), Humboldt-Universität zu Berlin, Unter den Linden 6, 10099 Berlin, Germany;4. Biomaterials, Hierarchical Structure of Biological and Bio-inspired Materials, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany |
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| Abstract: | A new hetero-bimetallic polyoxometalate (POM) nano-ring was synthesized in a one-pot procedure. The structure consists of tetrameric units containing four bismuth-substituted monolacunary Keggin anions including distorted BiO8] cubes. The nano-ring is formed via self-assembly from metal precursors in aqueous acidic medium. The compound (NH4)16(BiPMo11O39)4] ? 22 H2O; (P4Bi4Mo44) was characterized by single-crystal X-ray diffraction, extended X-ray absorption fine structure spectroscopy (EXAFS), Raman spectroscopy, matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF), and thermogravimetry/differential scanning calorimetry mass spectrometry (TG-DSC-MS). The formation of the nano-ring in solution was studied by time-resolved in situ small- and wide-angle X-ray scattering (SAXS/WAXS) and in situ EXAFS measurements at the Mo?K and the Bi?L3 edge indicating a two-step process consisting of condensation of Mo-anions and formation of Bi?Mo-units followed by a rapid self-assembly to yield the final tetrameric ring structure. |
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| Keywords: | bismuth in?situ EXAFS in?situ SAXS/WAXS lacunary Keggin ion polyoxometalates self-assembly |
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