Grand canonical Monte Carlo simulations
To have a better insight into the excellent C2H2 separation ability of Zn2(bpy)(btec), GCMC simulations were performed to structurally elucidate how C2H2molecules are adsorbed in this MOF.35,37,38 The calculated binding sites of C2H2 are shown in Figure 6. The C2H2 molecules are preferentially located in the pore cavities between the layers of Zn2(bpy)(btec). The C–H···O hydrogen bonds of each C2H2 molecule interacts with two oxygen molecule with a distance of 2.2~2.33 Å, which are much shorter than the sum of the van der Waals radii of oxygen (1.52 Å) and hydrogen (1.20 Å) atoms, indicating a relatively strong interaction.