Introduction of an amino group on zeolitic imidazolate framework through a ligand-exchange reaction

We newly synthesized an amino-functionalized zeolitic imidazolate framework (ZIF), [Zn{(dmamIM)n(mIM)m}2] (dmamIM-: 2-[(dimethylamino)methyl]imidazolate; mIM-: 2- methylimidazolate), through a ligand-exchange reaction using an amino-functionalized ligand, dmamIM-, and ZIF-8 as a mother framework. Original ligand of ZIF-8, mIM-, was partially replaced with the dmamIM-under various solvothermal conditions. The crystal structures of resultant specimens were analyzed by Rietveld method combined with maximum entropy method using synchrotron X-ray powder diffraction patterns. Porous characters of the compound were examined using adsorption measurements and alternate-current impedance measurements. The ligand exchange was found to occur as an equilibrium reaction in the reaction solutions. The reaction rate deeply depends on the types of solvents and the introduced ligands are homogeneously distributed on the sodalite-type framework.