Coordination Cage-Based Emulsifiers: Templated Formation of Metal Oxide Microcapsules Monitored by In Situ LC-TEM |
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Authors: | Dr Subhadeep Saha Dr Yen-Ting Chen Dr Sudhakar Ganta Markus Gilles Björn Holzapfel Dr Pascal Lill Prof Dr Heinz Rehage Prof Dr Christos Gatsogiannis Prof Dr Guido H Clever |
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Institution: | 1. Department of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn Straße 6, 44227 Dortmund, Germany;2. Center of Molecular Spectroscopy and Simulation of Solvent-driven Processes (ZEMOS), Ruhr-University, Bochum, 44801 Bochum, Germany;3. Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn Straße 11, 44227 Dortmund, Germany;4. Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn Straße 11, 44227 Dortmund, Germany
Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, Westfälische Wilhelms-University Münster, Busso-Peus Str. 10, 48149 Münster, Germany |
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Abstract: | Metallo-supramolecular self-assembly has yielded a plethora of discrete nanosystems, many of which show competence in capturing guests and catalyzing chemical reactions. However, the potential of low-molecular bottom-up self-assemblies in the development of structured inorganic materials has rarely been methodically explored so far. Herein, we present a new type of metallo-supramolecular surfactant with the ability to stabilize non-aqueous emulsions for a significant period. The molecular design of the surfactant is based on a heteroleptic coordination cage ( CGA-3 ; CGA =Cage-based Gemini Amphiphile), assembled from two pairs of organic building blocks, grouped around two Pd(II) cations. Shape-complementarity between the differently functionalized components generates discrete amphiphiles with a tailor-made polarity profile, able to stabilize non-aqueous emulsions, such as hexadecane-in-DMSO. These emulsions were used as a medium for the synthesis of spherical metal oxide microcapsules (titanium oxide, zirconium oxide, and niobium oxide) from soluble, water-sensitive alkoxide precursors by allowing a controlled dosage of water to the liquid-liquid phase boundary. Synthesized materials were analyzed by a combination of electron microscopic techniques. In situ liquid cell transmission electron microscopy (LC-TEM) was utilized for the first time to visualize the dynamics of the emulsion-templated formation of hollow inorganic titanium oxide and zirconium oxide microspheres. |
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Keywords: | coordination cages emulsions metal oxides self-assembly transmission electron microscopy |
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