Molecular simulations have largely contributed to the emergence of Metal Organic Frameworks (MOFs) not only for the resolution of the crystal structures of the most complex and poorly crystallized solids but also to enumerate all the plausible structures constructed by the assembly of a large diversity of inorganic and organic building blocks. Besides this in silico design of novel MOFs which has been only rarely validated so far by the post-synthesis of the desired material, a computational effort has been deployed to modulate the chemical and topological features of existing architectures specifically targeted for societally-relevant applications. Molecular modelling has been also frequently used to guide interpretation of the experimental data by providing a deep understanding of the microscopic adsorption/separation mechanism with the objective to drive the synthesis effort towards tuned materials with the required features for an optimization of their properties. This presentation will highlight the invaluable contribution of the computational approaches from the birth of novel MOFs and their structure elucidations to the characterization and understanding of their properties, throughout recent advances our groups have made in this field. A special emphasizes will be devoted to a series of recent MOFs that show promising adsorption/separation performances for natural gas upgrading, carbon capture and interesting features for mechanical energy storage and proton conduction.
We study the inverse boundary value problem for the Helmholtz equation using the Dirichlet-to-Neumann map at selected frequencies as the data. A conditional Lipschitz stability estimate for the inverse problem holds in the case of wavespeeds that are a linear combination of piecewise constant functions (following a domain partition) and gives a framework in which the scheme converges. The stability constant grows exponentially as the number of subdomains in the domain partition increases. We establish an order optimal upper bound for the stability constant. We eventually realize computational experiments to demonstrate the stability constant evolution for three-dimensional wavespeed reconstruction
The proton-conduction performances of the chemically stable porous zirconium phenolate MIL-163 MOF were characterized for the first time by complex impedance spectroscopy. Whereas this large square-shaped channel-like MOF exhibits very poor conductivity under anhydrous conditions, measurements performed at 90 °C and 95% relative humidity evidenced a superprotonic behavior with a conductivity of 2.1 × 10 −3 S•cm −1 , among the highest values reported so far for waterstable MOFs. This experimental investigation was further supported by Monte Carlo simulations to shed light on the effects of both the guest molecules (i.e., dimethylamine and water) and the acidic protons from the constitutive inorganic chains on the conduction properties of this porous hybrid solid. It was found that the water molecules form a three-dimensional hydrogen-bond network leading to the formation of multiple pathways that bridge the acidic Zrbonded phenol groups of the organic linker, which act as a proton source. The dimethylamine molecules were revealed to form single hydrogen bonds with H 2 O without leading to a disruption of the water hydrogen-bond network. This offers an optimal situation for the water-mediated transfer of protons over long distances at the origin of the good proton-conducting performance of MIL-163.
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