Highly Stable and Bifunctional Bio-inspired Catalytic MOFs for Destruction of Chemical Threats.
Abstract
Using new materials chemistry and predictive computational modeling capabilities developed by the team members, we propose to design, engineer, and construct highly porous metal-organic frameworks (MOFs) that exhibit unprecedented chemical stability and outstanding potential for bio-inspired degradation/inactivation catalysis (hydrolysis/oxidation) of nerve agents and simulants. Introduction. Enzymes are exquisite catalysts for an extraordinarily broad range of metabolically relevant chemical and biochemical transformations. Notably, these transformations include selective hydrolysis, oxidation, and other reactions that are of obvious interest for destruction of chemical threats. The "best" enzymes are capable of simultaneously achieving high specificity, high turnover frequency, and high turnover number. Additionally, they can be readily coupled to other catalytic cycles to carry out complex chemical transformations. Interestingly, the coupled catalyst sites are often intrinsically incompatible. Protein architectures, however, serve to isolate these sites while simultaneously creating molecule-accessible channels between them. Given these exceptional properties, enzymes would, at first glance, appear to be perfect catalysts for DoD applications such as destruction of chemical and biological threats. In practice, however, there exist severe limitations to enzymes in abiotic applications including: i) irreversible denaturation and loss of catalytic activity at elevated temperature or when deployed in non-aqueous or non-biological media, ii) large areal and volumetric requirements (due to the typically large sizes of protein architectures relative to activesite dimensions), iii) difficulty in rationally modifying systems to enable effective abiotic application, and iv) excessive substrate specificity. A seemingly obvious solution would be to design and build artificial analogues of naturally occurring enzymes. An ideal artificial enzyme would have the following properties: facile assembly; high turnover frequency and turnover number; retention of high catalytic activity at thermal extremes; excellent chemical stability; synthetic tunability of active sites, co-factors, and cavity environment, thereby allowing for catalyst performance optimization for a broad range of candidate reactants; understandable mechanisms of catalysis, allowing for predictive modeling of the catalytic system for performance optimization for a broad range of candidate reactants; and finally, an ideal artificial enzyme would perform well at ambient temperature and would be capable of using simple, environmentally accessible reagents such as water and dioxygen to carry out desired catalytic transformations-for example, hydrolysis/oxidation of chemical warfare agents and/or improvised chemical threats. We seek to build on very recent discoveries in our labs in the area of synthesis and modeling of extraordinarily robust and extraordinarily catalytic metal-organic framework (MOF) materials
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 23, 2018
- Source ID
- HDTRA11810003
Entities
People
- Omar Farha
Organizations
- Defense Threat Reduction Agency
- Northwestern University