Converting Metal–Organic Framework Particles from Hydrophilic to Hydrophobic by an Interfacial Assembling Route

Here, we propose to modify the hydrophilicity of metal–organic framework (MOF) particles by an interfacial assembling route, which is based on the surface-active nature of MOF particles. It was found that hydrophilic UiO-66-NH 2 particles can be converted to hydrophobic particles through an oil–water interfacial assembling route. The underlying mechanism for the conversion of UiO-66-NH 2 was investigated by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. It was revealed that the close assembly of UiO-66-NH 2 particles at the oil–water interface strengthens the coordination between organic ligands and metal ions, which results in a decrease in the proportion of hydrophilic groups on UiO-66-NH 2 particle surfaces. Hydrophobic UiO-66-NH 2 particles show improved adsorption capacity for dyes in organic solvents compared with pristine UiO-66-NH 2 particles. It is expected that the interfacial assembling route can be applied to the synthesis of different kinds of MOF materials with tunable hydrophilicity or hydrophobicity required for diverse applications.