(638h) Ring And Branched Amino Acids For Templating Mesoporous Cerium Oxide: Synthesis And Structural Characterization

Self assembly mechanisms for the synthesis of inorganic materials with control over the final structure are of major interest for their ability to create novel architectures and to induce new properties. Metal oxides with hierarchical nanoarchitectures are synthesized by different methods and using several types of structure directing agents [1]. Recently, simple amino acids had been used to form controlled mesoporous structures in metal oxides [2]. However, it is not clear how the structure of the amino acid is controlling the final structure of the metal oxide. The focus of this research is on the controlled synthesis of nanostructured metal oxides, specifically cerium oxide, templated with amino acids. We explore the effects of ring and branched amino acids on the final structure of cerium oxide and its chemical properties. The use of Raman micro-spectroscopy characterization to determine the crystallite sizes of the nanostructured cerium oxide [3,4] is exemplified with our results. The samples were characterized by XRD, TEM, N₂ adsorption, H₂ adsorption, TGA, and Raman spectroscopy. In this talk, we will present results showing that all the amino acid-templated samples presented ordered structures with crystallite sizes in the range of 10?30 nm as determined by XRD, TEM, and Raman spectroscopy. Furthermore, it was found that among the amino acids tested, the ring structured proline and the branched valine provide the smallest and most homogeneous nanostructured cerium oxide.

References: 1. Leininger, S.; Olenyuk, B.; Stang, P. J.; Chem. Rev. 2000, 100; 853. 2. Zhang, G.; Shen, Z.; Liu, M.; Guo, C.; Sun, P.; Yuan, Z.; Li, B.; Ding, D.; and Chen, T.; J. Phys. Chem. B 2006, 110, 25782. 3. Spanier, J. E.; Robinson, R. D.; Zheng, F.; Chan, S. W.; Herman, I. P.; Physical Review B 2001, 64, 245407. 4. Guzman, J.; Carrettin, S.; and Corma, A.; J. Am. Chem. Soc. 2005, 127, 3286.