Impact of solvent substitution on kinetically controlled transmetalation behaviours in a MOF

Abstract

Using post-synthetic modification (PSM), in this work, we investigated the effects of different solvents on central ion exchange behaviours, i.e., Zn²⁺ by Mn²⁺ ions, in TIF-4. Based on the scanning electron micrographs, powder X-ray diffraction patterns, calorimetric behaviours, together with the various solvent parameters, the chemical origin of solvent dependence of transmetalation extent was revealed. Furthermore, focusing on the solvent EtOH, which has the maximum exchange extent, we discovered an interesting amorphization phenomenon induced by the kinetically-driven transmetalation process, which could be ascribed to the gradually increased strain in crystal lattice with the substitution of Zn²⁺ by Mn²⁺. This work provides a deeper insight into the PSM process in MOF materials, which is helpful to tune the structure and properties of MOFs.