indicates that those Zr cus sites are stronger Lewis acids and should bind more strongly to nucleophiles in GO. Then, we proceeded by placing GO in close proximity to Zr sites in each cluster (input files are provided as supplementary data) and relaxing the structures to find local energetic minima. The binding energies of the relaxed structures are plotted in Figure . A few key observations emerged. First, creating high-valent Zr states by binding to a ZrO 8 site in g 0 is energetically unfavorable, as GO moved away from the cluster to lower the overall energy. Next, like in the pristine cluster, GO moved away from the missing-linker cluster, g 1,1 , if we did not free up an adsorption site on Zr by removing a terminal water group. Several previous studies have indicated that reactions on {Zr 6 } clusters and nanocrystals occur through ligand exchange mechanisms. By doing this substitution, we ended up with a relatively low binding energy of BE = -97.49 kJmol -1 .