Metal-Organic Scandium Framework: Useful Material for Hydrogen Storage and Catalysis Josefina Perles, Marta Iglesias, Maria-A Ä ngeles Martı ´n-Luengo, M. A Ä ngeles Monge,* Caridad Ruiz-Valero,* and Natalia Snejko Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid, Spain ReceiVed June 23, 2005. ReVised Manuscript ReceiVed August 11, 2005 The 3D polymeric terephthalate of scandium has been synthesized and its structure solved by single- crystal XRD. It was obtained as a single phase and characterized and tested as a hydrogen and nitrogen adsorbent and heterogeneous catalyst as a redox agent in the oxidation of sulfides. The compound shows a BET area of 721 m 2 g -1 with a high C BET ) 7000. The high chemical and thermal stability and excellent hydrogen sorption properties make this compound a useful material for hydrogen storage. Introduction Hydrogen would be ideal as a synthetic fuel because it is lightweight and highly abundant and its oxidation product (water) is environmentally benign, but storage remains a problem. The major obstacle for the commercial use of hydrogen-based fuel-cell vehicles is on-board hydrogen storage. Different approaches are used to overcome difficul- ties in storing and using gaseous hydrogen in high-pressure vessels appropriate for stationary or mobile applications. Among the materials under investigation, complex hydrides, carbon and nongraphitic nanotubes, and finally metal- organic frameworks 1 are found, the last being the less studied yet. It is a well-known fact that rare-earth-containing com- pounds can be used as strong and effective catalysts. However, despite the rich chemistry of rare-earth open frameworks, it is remarkable that there are only a few works 2-4 dedicated to the research of their catalytic activity. Sulfoxides are important intermediates of many natural products. 5 Their synthesis has been achieved by means of a wide range of oxidizing systems, starting from the corre- sponding sulfides. Aqueous hydrogen peroxide is a particu- larly attractive oxidant, since it is cheap, environmentally friendly, and easy to handle and produces only water as a byproduct, which reduces purification requirements. The catalysts, often used to enhance the efficiency of the oxidation, are mostly metal salts (chlorides, oxides, perox- ides, acetates, and acetyl acetonates of Ti, V, Mo, W, Re, and Mn). They play a very important role as catalytic activators of hydrogen peroxide: the resulting metal-peroxo derivatives are such powerful catalysts that usually give rise to overoxidized byproducts. Lanthanides have scarcely been explored in the oxidation of thioethers, yet these elements are receiving increasing attention in the literature. 6 Three-dimensional coordination polymers of rare earths and transition metals have received significant attention in the past few years because of their potential useful attributes, such as magnetism, zeolite-like catalytic activity, and optical properties. 7 Among the available ligands to form these compounds, the dicarboxylic acids present interesting com- plexing behavior due to the diverse modes of coordination: in particular, terephthalate anion (1,4-benzenedicarboxylate) can bridge either in a bidentate or a monodentate fashion and may be completely or partially deprotonated. The dicarboxylic acids have many possibilities in coordinative behavior, even with large coordination numbers of the metallic center. The resulting coordination polymers are materials in which the properties of individual components are combined. 8 Terephthalic acid has been successfully used to build coordination architectures with metal ions of diverse sizes and shapes, adopting different coordination fashions. 9 * To whom correspondence should be addressed. Phone: +34 91 334 90 25. Fax: +34 91 372 06 23. E-mail: amonge@icmm.csic.es (M.A Ä .M.), crvalero@icmm.csic.es (C.R.-V.). (1) Rossi, N. L.; Eckert, J.; Eddaoudi, M.; Vodak, D. T.; Kim, J.; O’Keeffe, M.; Yaghi, O. M. Science 2003, 300, 1127. (2) Perles, J.; Iglesias, M.; Ruiz-Valero, C.; Snejko, N. Chem. Commun. 2003, 3, 346. (3) Perles, J.; Iglesias, M.; Ruiz-Valero, C.; Snejko, N. J. Mater. Chem. 2004, 14, 2683. (4) Snejko, N.; Cascales, C.; Go ´mez-Lor, B.; Gutie ´rrez-Puebla, E.; Iglesias, M.; Ruiz-Valero, C.; Monge, A. Chem. Commun. 2002, 13, 1366-1367. (5) Prilezhaeva, E. Russ. Chem. ReV. 2002, 4, 715. (6) Kagan, B. Chem. ReV. 2002, 102, 1805. 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