2) Adsorption of water. Adsorption of water and water stability of porous materials has been one of the most significant factors when considering adoption of materials for carbon capture applications. Currently available materials such as 13X strongly adsorb water and this leaves two options for their use in carbon capture: either there is a separate adsorption stage to preprocess the flue stream and remove water; or, alternatively, the current process runs as is, leading to some water accumulating in the column and the process overall running at lower efficiency (hence, lower productivity and higher energy cost, potentially rendering the whole approach unfeasible). In fact, one of the key aspects of the CALF-20 success story is its apparent lack of affinity towards water while retaining high affinity for CO2. Recent combined experimental and simulation studies by Oktavian et al. suggest that this effect is associated with the geometry of the pore space of CALF-20, preventing water from forming fully coordinated hydrogen bond networks (each molecule of water can form only two hydrogen bonds). Recognizing the challenge of water interfering with the adsorption of carbon dioxide, Boyd et al. also designed and realized materials maintaining high CO2/N2 selectivity that persists under conditions of wet flue gases. Here, again it is the geometry of pores that makes the environment hydrophobic for water due to constraints imposed on the formation of hydrogen bonds. The materials proposed here have not been tested for potential water adsorption or for water stability. We can anticipate that this factor will be quite important for the larger pore MOFs and it would be interesting to search within this group of MOFs for pore architectures preventing formation of liquid-like water clusters.