Ligand and Metal Effects on the Stability and Adsorption Properties of an Isoreticular Series of MOFs Based on T-Shaped Ligands and Paddle-Wheel Secondary Building Units

Abstract

The synthesis of stable porous materials with appropriate pore size and shape for desired applications remains challenging. In this work a combined experimental/computational approach has been undertaken to tune the stability under various conditions and the adsorption behavior of a series of MOFs by subtle control of both the nature of the metal center (Co2+, Cu2+, and Zn2+) and the pore surface by the functionalization of the organic linkers with amido and N-oxide groups. In this context, six isoreticular MOFs based on T-shaped ligands and paddle-wheel units with ScD0.33topology have been synthesized. Their stabilities have been systematically investigated along with their ability to adsorb a wide range of gases (N2, CO2, CH4, CO, H2,light hydrocarbons (C1–C4)) and vapors (alcohols and water). This study has revealed that the MOF frameworks based on Cu2+are more stable than their Co2+and Zn2+analogues, and that the N-oxide ligand endows the MOFs with a higher affinity for CO2leading to excellent selectivity for this gas over other species.