Rational design of lanthanide-based metal-organic frameworks for CO capture using computational modeling.

Metal organic frameworks (MOFs) have emerged as promising materials in the context of CO capture and separation. Thanks to their tunable nature, various functionalities can be introduced to improve their separation performances. Lanthanide MOFs (Ln-MOFs) with high coordination numbers offer a promising space for the design of new high-performing and stable adsorbents for gas adsorption and separation. In this study, we combined molecular simulations with quantum mechanical (QM) calculations for designing new hypothetical materials offering superior CO/N separation performances. An Ln-MOF having high CO/N selectivity and working capacity was originally selected and its linkers were exchanged with five different types of linkers and its metal atom was exchanged with 12 different Ln metals to generate 77 different types of hypothetic Ln-MOFs. Following the initial geometry optimizations at the molecular mechanics (MM) level, these structures were studied for CO/N separation by performing grand canonical Monte Carlo (GCMC) simulations. Five MOFs were found to outperform the original Ln-MOF structure and they were optimized at the QM level to obtain geometries with minimized total energy, which finally led to two hypothetic Ln-MOFs offering superior CO/N separation performance. The computational work that we described in this study will be useful for the rational design of new Ln-based MOFs with improved CO separation properties.