An Electrochemical and Spectroscopic Characterization of Chiral MIL-53(Fe) Metal-Organic Framework

Abstract

Metal-organic frameworks (MOFs) have attracted increasing scientific interest due to unique features including high specific surface areas, exceptional porosity, high crystallinity and tuneable pore size [1]. In fact, the opportunity to achieve porous materials with high modularity and diverse functionality make MOFs suitable candidate for solid-state materials. In recent years, scientists conducted intense research in the production of chiral MOFs (CMOFs). The attractiveness of chiral MOFs is due to their specific application including chiral enantioselective recognition, enantioselective separation, asymmetric catalysis, and sensing. Chirality within MOFs can occur in each of the components, whether linker, metal node, or even guest molecules [2]. MIL-53(Fe) is the most common iron-based MOF. This class of compound is obtained by a combination between iron(III) cations and 1,4-dicarboxylic acid consists of three-dimensional networks which contain FeO6 hexagonal chains and dicarboxylate anions. MIL-53(Fe) shows significant advantages compared with other MOFs, which include chemical stability, the presence of nontoxic and widely available metals [3]. MIL-53(Fe) derivatives containing chiral molecules (cysteine and camphorsulfonic acid) were characterized by IR, XRD and Electron Spectroscopy. The electrochemical behaviour of the synthesized MOFs was characterized on solid state using a glassy carbon (GC) electrode and by making a paste with graphite powder. Cyclic voltammetry (CV) measurements show different redox behaviour depending on the type of molecules present inside the framework. The experimental results were integrated and related to the properties obtained using DFT based quantum mechanical calculations.