Abstract
We demonstrate a simple method for real-time monitoring of mechanochemical synthesis of metal–organic frameworks, by measuring changes in pressure of gas produced in the reaction. Using this manometric method to monitor the mechanosynthesis of the zeolitic imidazolate framework ZIF-8 from basic zinc carbonate reveals an intriguing feedback mechanism in which the initially formed ZIF-8 reacts with the CO2 byproduct to produce a complex metal carbonate phase, the structure of which is determined directly from powder X-ray diffraction data. We also show that the formation of the carbonate phase may be prevented by addition of excess ligand. The excess ligand can subsequently be removed by sublimation, and reused. This enables not only the synthesis but also the purification, as well as the activation of the MOF to be performed entirely without solvent.
Highlights
Mechanochemical reactions[1] have developed from a laboratory curiosity to a viable alternative to conventional solution-based chemistry, enabling room-temperature reactions without bulk solvents,[2] improved or previously unknown reactivity,[3] and routes to molecules and materials otherwise difficult to access.[4]
We demonstrate a simple method for real-time monitoring of mechanochemical synthesis of metal– organic frameworks, by measuring changes in pressure of gas produced in the reaction
Using this manometric method to monitor the mechanosynthesis of the zeolitic imidazolate framework zeolitic imidazolate frameworks (ZIFs)-8 from basic zinc carbonate reveals an intriguing feedback mechanism in which the initially formed ZIF-8 reacts with the CO2 byproduct to produce a complex metal carbonate phase, the structure of which is determined directly from powder X-ray diffraction data
Summary
Mechanochemical reactions[1] have developed from a laboratory curiosity to a viable alternative to conventional solution-based chemistry, enabling room-temperature reactions without bulk solvents,[2] improved or previously unknown reactivity,[3] and routes to molecules and materials otherwise difficult to access.[4] Ball milling, twin screw extrusion,[5] and accelerated aging[6] have been applied successfully for the synthesis of diverse Metal– Organic Frameworks (MOFs),[7] including carboxylate-based HKUST-1,8 MOF-74 9 and IRMOF materials,[10,11] zeolitic imidazolate frameworks (ZIFs),[12] and zirconium-based UiO- and NUsystems.[13] Importantly, mechanochemistry permits simple, room-temperature and solvent-free assembly of MOFs from metal oxides, carbonates or other basic salts: reagents that are Despite the rapid growth of applications of mechanochemistry in chemical and materials synthesis, the underlying reaction mechanisms and kinetics remain poorly understood, and it was not until 2013 that methodologies for direct, in situ monitoring of such transformations were reported, using powder Xray diffraction (PXRD) and/or Raman spectroscopy.[17] other simpler methods have been employed for monitoring mechanochemical reactions, in cases where direct acquisition of structural data is not required One of these methods is monitoring the pressure and temperature of a gaseous reactant or product in a reaction vessel of constant volume – manometric monitoring. The Borchard group used monitoring of evolved HCl gas as a way to follow the course of a mechanochemical Scholl reaction,[25] and thermally-induced increase in gas pressure was used to detect highly exothermic reactions,[26] demonstrating the potential for a broader
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
