Metal-Organometallic Frameworks Supporting Catalytically Active Moieties

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TECHNICAL SUMMARY:This project is supported by the Solid State and Materials Chemistry (SSMC) program in the Division of Materials Research (DMR). Metal-organic frameworks (MOFs) have for some years now been at the forefront in the discovery of new materials with applications dependent upon the exhibition of porosity. The supported research of Professor K. Travis Holman and coworkers at Georgetown University is synergistic with, but atypical of, the extensive efforts in metal-organic framework (MOF) chemistry to date. The work aims to develop microporous metal-organometallic frameworks (MOMFs) possessing metallocyclopentadienyl or metalloarene substituents, ultimately for use in heterogeneous catalysis. The research will involve the development of new families of aryl carboxylate ligands to which are appended various organometallic moieties. In analogy to the exploitation of aryl carboxylate ligands to sustain microporosity in traditional MOF materials, a large number of metal-organometallic frameworks can be derived from the new organometallic arylcarboxylates. Preliminary data shows that the organometallic ligands are fully compatible with MOF syntheses, microporous MOMFs with large pore volumes can be achieved, and new and/or existing MOF architectures can sustain the organometallic moieties in question. The resulting MOMFs are and will thereby be engendered with organometallic moieties that are feasible chemical precursors to known organometallic catalysts. Efforts will be directed at the post-synthetic activation of these moieties for application as heterogeneous catalysis for a wide range of atom-economic organic transformations. Activation parameters and benchmark reactions will be studied. The proposal seeks to significantly broaden the range of available heterogeneous MOF-based catalysts and extend them to hitherto unstudied reactions in porous materialsNON-TECHNICAL SUMMARY:Microporous materials - that is, those that possess permanent, accessible channels on the size-scale of individual small molecules ( 2 nm) find a host of applications in industrial settings: ion-exchange, selective sorption, separations, important large and small scale chemical transformations, etc. They are integrated into the world economy on a large scale and new microporous materials with improved performance in a variety of traditional and emerging areas (e.g., fuel cell membrane technology, separations and fuel refinement technologies, CO2 sequestration, other forms of environmental remediation including nuclear waste remediation, gas/fuel storage, commodity and specialty chemicals) are continually being developed. Metal-organic frameworks (MOFs) have emerged in the past 15+ years as probably the most promising class of new microporous materials and, of the many rapidly emerging applications for MOFs, one of the most promising is in their use as heterogeneous catalysts - i.e. to facilitate new, commercially relevant chemical transformations. With support from the Solid-State and Materials Chemistry program in the Division of Materials Research, this project seeks to dramatically expand the scope of MOF materials through the development of a new family of analogous materials that can be described as metal-organometallic frameworks (MOMFs). MOMFs will integrate important known and emerging catalysts into microporous MOF architectures leading to enhanced chemical properties and greater industrial compatibility for these catalysts. The funds will support the education of five PhD student-years, several undergraduate students, and high school students. The project also seeks to broaden the impact of this materials-oriented work via educational outreach on multiple fronts. The proposed work attempts to significantly contribute to the NSF's mission to promote achievement and progress in science/engineering and its potential to contribute to the Nation by integrating educational development and basic research that is impactful to the nation's various chemical technologies.