We now use molecular simulations to predict the Xe, Kr, and Ar Henry coefficients at K in each structure in our Ni(PyC-X) 2 library-using the same molecular model that produced simulated adsorption isotherms matching experimental measurements in the parent MOF in Fig. . See Sec. . . for details. The Xe/Kr selectivity (at dilute conditions) follows from the ratio of the Xe to Kr Henry coefficients. Fig. shows the results of our computational screening by displaying the performance of each Ni(PyC-X) 2 MOF in our library. For Xe/Kr separations, we wish for a MOF to exhibit both a high Xe/Kr selectivity and a high Xe uptake (a high Henry coefficient, at dilute conditions). Thus, the most desirable MOFs reside in the top-right quadrant of the commercial availability of the PyC-m-NH 2 ligand .