In silico design of a new Zn-triazole based metal-organic framework for CO and HO adsorption.

In search for future good adsorbents for CO capture, a nitrogen-rich triazole-type Metal-Organic Framework (MOF) is proposed based on the rational design and theoretical molecular simulations. The structure of the proposed MOF, named Zinc Triazolate based Framework (ZTF), is obtained by replacing the amine-organic linker of MAF-66 by a triazole, and its structural parameters are deduced. We used grand-canonical Monte Carlo (GCMC) simulations based on generic classical force fields to correctly predict the adsorption isotherms of CO and HO. For water adsorption in MAF-66 and ZTF, simulations revealed that the strong hydrogen bonding interactions of water with the N atoms of triazole rings of the frameworks are the main driving forces for the high adsorption uptake of water. We also show that the proposed ZTF porous material exhibits exceptional high CO uptake capacity at low pressure, better than MAF-66. Moreover, the nature of the interactions between CO and the MAF-66 and ZTF surface cavities was examined at the microscopic level. Computations show that the interactions occur at two different sites, consisting of Lewis acid-Lewis base interactions and hydrogen bonding, together with obvious electrostatic interactions. In addition, we investigated the influence of the presence of HO molecules on the CO adsorption on the ZTF MOF. GCMC simulations reveal that the addition of HO molecules leads to an enhancement of the CO adsorption at very low pressures but a reduction of this CO adsorption at higher pressures.