Sustainable Metallocavitand for Flue Gas-Selective Sorption: A Multiscale Study

We have used density functional theory, Grand canonical Monte Carlo (GCMC), and ideal adsorption solution theory (IAST) to understand the selective adsorption of flue within the cavity of porous metallocavitand pillarplex (PPX) molecule. Energies associated with the guest@PPX complex formation depict the effectiveness of encapsulation of guest within PPX. PPX is noted to have high selectivity toward the adsorption of Br2, HBr, CS2, H2S, and NO2 over their respective congeners. The strength of bonding and nature of the interaction is deciphered via quantum theory of atoms in molecule, noncovalent interaction, and energy decomposition analysis scheme. The molecules containing acidic hydrogen, viz., H2O, H2S, HF, HCl, and HBr, make hydrogen bonding with the −N atom of the pyrazole ring, and F2 and Cl2 make partially covalent bonding interaction with the −Au atom of PPX. The interaction is mostly of the van der Waals type, except in F2, Cl2, NO, and HF, in which the cumulative contribution of orbital, electro...