Post-synthetic metal-ion metathesis in a single-crystal-to-single-crystal process: improving the gas adsorption and separation capacity of an indium-based metal–organic framework

Abstract

A polyhedral metal–organic framework (MOF) JLU-Liu40-In based on dual secondary building units (SBUs) of mononuclear and binuclear paddlewheel indium has been prepared with a nitrogen-rich tetracarboxylic acid ligand under solvothermal conditions. Since the framework possesses large surface areas with multiple polyhedral cages, abundant open metal sites (OMSs) and Lewis basic sites (LBSs), it exhibits high performance for gas adsorption. In addition, through post-synthetic metal-ion metathesis in a single-crystal-to-single-crystal (SCSC) process, JLU-Liu40-In/Cu has been obtained by selectively substituting the paddlewheel In(III) ions with Cu(II) ions without replacing the mononuclear In(III). The framework remains in the form of a single crystal throughout the process. It is worth noting that the metal-ion metathesis approach constructs JLU-Liu40-In/Cu with a significant improvement in thermal stability and gas sorption and separation.