Computational evaluation of MOFs for their adsorption and catalytic degradation performances with respect to chemical warfare agents

Abstract

The present PhD thesis aims to perform a computational evaluation of a large series of Metal Organic Frameworks (MOFs) containing Zr or Ti as the metal centers for their adsorption and degradation performances with respect to chemical warfare agents: nerve agents (Sarin and Soman), vesicant agents (Sulfur Mustard) as well as their simulants, Dimethyl methylphosphonate, Diisopropyl phosphorofluoridate, Pinacolyl methylphosphonate and 2- Chloroethyl ethyl sulfide. This was achieved by combining Density Functional Theory (DFT) calculation and Monte Carlo simulations to assess the adsorption uptake, the energetics and the preferential adsorption sites for each considered MOF/CWA pair. The rationalization of the sogenerated database was further achieved in order to establish structure-adsorption property relationships with the consideration of geometric and electronic descriptors characterizing MOFs, CWAs as well as CWA/MOF interactions. As a further step, DFT calculations were performed to elucidate the degradation mechanisms for CWAs and their simulants on the Ti or Zr-MOFs analyzing the main states of the degradation reaction and the resulting activation energies. Finally, the hydrolysis mechanism of a series of Zr and Ti-MOFs was explored by means of DFT calculations with the objective to identify the key parameters that control their stability under humidity. This computational work is expected to pave the way towards refined MOFs with improved capture/degradation performances to be potentially applied as CWA filters.