Strategies for Characterization of Large-Pore Metal-Organic Frameworks by Combined Experimental and Computational Methods

Abstract

A large-pore IRMOF-16-like material (1) was synthesized solvothermally and evacuated by two solvent removal procedures: the original chloroform (CHCl3) method and a new supercritical carbon dioxide (SCD) method. Using several experimental and geometric characterization tools, including thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), and pore size analysis, we propose that 1 is a mixture of noncatenated IRMOF-16 and the corresponding 2-fold interwoven structure and is partially collapsed during the evacuation, especially some of the larger pores. Adsorption measurements using several gases at 77 and 298 K showed that the new SCD evacuation is superior to the conventional CHCl3 evacuation for increasing the adsorption kinetics as well as the adsorption capacity. This work illustrates a new strategy that combines several experimental methods, geometric calculations, and molecular simulations for the characterization of metal-organic frameworks (MOFs), especially those with large pores. This combination should be helpful for future characterization of new MOFs that possibly include some imperfections such as nonuniform catenation and partial collapse of the crystalline phase.