Omar M. Yaghi

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Prof. Omar M. Yaghi

Dr. Omar M. Yaghi (born 1965) is an American chemist currently a Professor at the Department of Chemistry and Biochemistry at University of California-Los Angeles [1]. He is widely considered to be the inventor and world’s leading authority on the chemistry and applications of Metal-Organic Framework (MOFs) [1] [2][2]. MOFs hold many records among them that of MOF-177 having the highest surface area (5,640 m2/g) [3]. He has successfully developed these materials from basic science to application in clean energy technologies (hydrogen storage, methane storage, carbon dioxide capture). Recently, he and his group have succeeded in inventing another equally extensive class of porous materials termed Covalent Organic Frameworks (COFs), and Zeolitic_imidazolate_frameworks (ZIFs) [3]. A member of the COF class, COF-108, has the lowest density known for any crystal (0.17 g/cm3)[4]. His efforts and contributions have been recognized by numerous awards and honors among them Materials Research Society Medal for pioneering work in the theory, design, synthesis and applications of metal-organic frameworks and the AAAS Newcomb Cleveland Prize for the best paper published in Science (2006-2007) and for outstanding contributions to Science.

[edit] Biography

Omar M. Yaghi received his Ph.D. from the University of Illinois-Urbana [4] (1990) with Professor Walter G. Klemperer. He discovered the first known inorganic host-guest complex, (V12O32)-4, [5], and studied the kinetics and thermodynamics of its inclusion chemistry. This compound inspired the development of many vanadium oxide polyhedra compounds. In 1990 he moved to Harvard University [5] as an NSF Postdoctoral Fellow with Professor Richard H. Holm. While at Harvard he succeeded in establishing the chemistry of excising transition metal sulfide and selenide clusters from extended structures in which such clusters are linked by strong halide bridges. The excised clusters were inaccessible using traditional methods of synthesis. His interest in developing the molecular building block approach as means of creating new crystalline extended structures, led him to accept a position on the faculty at Arizona State University [6] in 1992 as Assistant Professor of Chemistry. Within the first 2 years of his stay at ASU, he showed the feasibility of deliberately designing and synthesizing crystalline materials from molecular building blocks by making the first porous metal sulfides [6]. He extended this strategy to the synthesis of metal-organic frameworks (MOF) which is now an extensive class of materials. The structures of MOFs are constructed from metal-oxide ‘hubs’ that are linked by organic ‘struts’ to make open structures. He received the ACS-Exxon Solid-State Chemistry Award in 1998 for his unique contributions to Solid State Chemistry. In 1999, he moved to the University of Michigan [7] as the Robert W. Parry Collegiate Professor of Chemistry (1999) and shortly thereafter was awarded the Sacconi Medal by the Inorganic Division of the Italian Chemical Society for his work on hydrogen storage in MOFs. Since January 2006, he has been the Christopher S. Foote Professor of Chemistry and Biochemistry at UCLA [8], Director of the Center for Reticular Chemistry [9], and Director of the Clean Energy Network at the California NanoSystems Institute [10], UCLA. Recently he was listed among the "Brilliant 10" [11] in the USA by Popular Science magazine. He received the Materials Research Society Medal [12] for pioneering work in the theory, design, synthesis and applications of metal-organic frameworks and the AAAS Newcomb Cleveland Prize [13] for the best paper published in Science (2006-2007) and for outstanding contributions to Science. He has published over 100 papers which have received an average of over 100 citations per paper. He is listed among the top 0.25% cited chemists worldwide (No.15 of over 6,000 chemists) worldwide) [14] for his work on the design and construction of chemical structures using the molecular building blocks. This work has led to a number of new classes of useful porous materials such as metal-organic frameworks, covalent organic frameworks, and zeolitic imidazolate frameworks. He has succeeded in establishing the chemistry of linking molecular building block into extended structure using strong bonds; a field he named Reticular Chemistry. Currently, materials prepared using this chemistry are numerous and are being investigated by over 200 groups in academia, industry and government. Recently, BASF, the largest chemical company in the world, has begun commercializing MOFs (mof.basf.com) for catalysis, gas storage and gas separations. He continues to pursue basic science of porous discrete and extended structures and their applications in clean energy (hydrogen storage, methane storage, carbon dioxide capture), mechanical switching, catalysis, and gas separation technologies.

[edit] Research

MOFs

Metal Organic Frameworks (MOFs)


Design of framework structures in which metal oxides clusters act as 'hubs' and the organic linkers as 'struts' to produce highly porous crystals (ca. 6,000 m2/g) with the lowest density ever recorded for a crystalline material. These remarkable properties are found to be useful in gas storage, in particular hydrogen and methane storage for fueling automobiles, laptops, cellular phones and other mobile electronics. At present some MOFs are being prepared inexpensively in kilogram quantities[7].




MOPs

Metal Organic Polyhedra (MOPs)


Nano-sized metal-organic polyhedra (MOPs) are conveniently achieved by linking transition metal ions and either nitrogen or carboxylate donor organic units. Recently, the porosity of MOPs to gases and other molecules has been demonstrated; an important step towards their ultimate utility.1a,b Further progress in this area hinges on our ability to functionalize the surface of such particles and to assemble them on substrates or polymer films for device fabrication[8].



Covalent Organic Frameworks (COFs)


COF

The design and synthesis of crystalline extended organic structures in which the building blocks are linked together by strong covalent bonds is an undeveloped area of research. It is widely believed that the required microscopic reversibility for crystallization of linked organic molecules into such solids is difficult if not impossible to achieve ('the crystallization problem'). The lack of crystalline cross-linked polymers is often cited as evidence in support of this view. Recently, we embarked on a program aimed at challenging this notion by constructing porous crystalline covalent organic frameworks (COFs) solely from light elements (H, B, C, N, and O) that are known to form strong covalent bonds in well established and useful materials such as diamond, graphite, and boron nitride. The successful realization of COF materials through molecular building blocks would provide the first covalent frameworks which can be functionalized into light-weight materials optimized for gas storage, photonic, and catalytic applications. Here, we report a general design strategy and its implementation for synthesis and crystallization of micro- and mesoporous crystalline COFs. These materials have rigid structures, exceptional thermal stabilities (up to 600 °C), low densities and exhibit permanent porosity with specific surface areas surpassing those of well-known zeolites and porous silicates. Furthermore, the synthesis of the first two members, COF-1 and COF-5, employs a simple 'one pot' procedure using mild reaction conditions that are efficient and high yielding[9].



Zeolitic Imidazolate Frameworks (ZIFs)


ZIFs

A large segment of the global economy (US$350 billion) is based on the use of crystalline microporous zeolites in petrochemical cracking, ion-exchange for water softening and purification, and in the separation of gases. Zeolite structures are composed of tetrahedral Si(Al)O4 units covalently joined by bridging O atoms to produce over 150 different types of framework. A long-standing challenge is to incorporate transition metal ions and organic units within their pores and, more desirably, to do so as an integral part of the zeolite framework. This would be useful in many catalytic applications as the pores would be lined with a high concentration of ordered transition metal sites whose electronic and steric properties can be tailored by functionalization of the organic links. However, the vision of achieving such a zeolite that combines these features remains largely unrealized. We outline a general synthesis of structures having zeolite framework topologies in which all tetrahedral atoms are transition metals and all bridging ones are imidazolate units[10][11].

[edit] References

  1. ^ K. Sanderson, Materials chemistry: Space invaders, Nature, 2007, 448, 764.
  2. ^ S. F. Robert, Framework Materials Grab CO2 And Researchers’ Attention, Science, 2008, 893, 319.
  3. ^ A.G. Wong-Foy, A.J. Matzger, O.M. Yaghi, Exceptional H2 saturation uptake in microporous metal-organic frameworks, J. Am. Chem. Soc., 2006, 128, 3494.
  4. ^ H. M. El-Kaderi, J. R. Hunt, J. L. Mendoza-Cortés, A. P. Côté, R. E. Taylor, M. O´Keeffe, O. M. Yaghi, Designed Synthesis of 3D Covalent Organic Frameworks. Science, 2007, 316, 268.
  5. ^ V. W. Day, W. G. Klemperer, O. M. Yaghi, Synthesis and Characterization of a Soluble Oxide Inclusion Complex, J. Am. Chem. Soc., 1989, 111, 5959.
  6. ^ O. M. Yaghi, Z. Sun, D. A. Richardson, T. L. Groy, Directed Transformation of Molecules to Solids: Synthesis of a Microporous Sulfide from Molecular Germanium Sulfide Cages, J. Am. Chem. Soc., 1994, 116, 807.
  7. ^ O. M. Yaghi, M. O'Keeffe, N. Ockwig, H. K. Chae, M. Eddaoudi, J. Kim, Reticular synthesis and the design of new materials, Nature, 2003, 423, 705.
  8. ^ H. Furukawa, J. Kim, K. E. Plass, O. M. Yaghi, Crystal Structure, Dissolution, and Deposition of a 5 nm Functionalized Metal-Organic Great Rhombicuboctahedron, J. Am. Chem. Soc., 2006, 128, 8398.
  9. ^ A. P. Côté, A. Benin, A. N. , Ockwig, A. J. Matzger, M. O. Keeffe, O. M. Yaghi, Porous, crystalline, covalent organic frameworks, Science, 2005, 310, 1166.
  10. ^ K. S. Park, A. P. Côté, J. Y. Choi, R. Huang, F. J. Uribe-Romo, H. K. Chae, M. O'Keeffe, O. M. Yaghi, Exceptional chemical and thermal stability of zeolitic imidazolate frameworks, Proc. Nat. Acad. Sci. USA, 2006, 103, 10186.
  11. ^ B. Wang, A. P. Côté, H. Furukawa, M. O’Keeffe, O. M. Yaghi, Colossal cages in zeolitic imidazolate frameworks as selective carbon dioxide reservoirs, Nature, 2008, 453, 207.
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