As cGG was found to be a side product of hydrolysis with HD-200-UiO-66-NH2, the nanoMOFs were further examined for their ability to catalyse the peptide bond formation between amino acids and small peptides. The condensation reaction can be promoted over hydrolysis simply by changing the solvent from water to methanol. Both HD-US-UiO-66-NH2 and HD-US-UiO-66 nanoMOFs showed the ability to promote amide bond formation in MeOH (Figure ), but the HD-US-UiO-66 exhibited much higher reactivity than the functionalized HD-US-UiO-66-NH2. Similar to the previous report, for both MOFs the intramolecular peptide bond formation was favored over intermolecular one between individual glycine molecules (Reaction 3, Figure ). Interestingly, the functionalized HD-US-UiO-66-NH2 was ineffective in forming cGG when starting from GG (Reaction 2), but the fact that cGG was observed in other two reactions shown in Figure , suggests that the efficiency of intramolecular bond formation is influenced by substrate interaction with the MOF, rather than a reduced catalytic activity. These differences in the interactions could be in influenced by the presence of the electron donating -NH2 on the MOF, as well as by the MOF pore sizes, as the functionalized MOF exhibits slightly smaller pores due to the steric hindrance of the -NH2, which increases the diffusion barrier of the substrate into and out of the pores of the MOF.