Synthesis and characterization of iron-clathrochelates and their applications in materials science

This thesis focuses on the design and the synthesis of mono- and dinuclear iron clathrochelate complexes and their applications in materials science. Dinuclear iron clathrochelate complexes can be synthesized in different oxidation states: i. as negatively charged FeII-FeII complexes or ii. as neutral FeII-FeIII complexes. These compounds display interesting magnetic properties. The negatively FeII-FeII complexes are antiferromagnetic, whereas the neutral FeII-FeIII complexes are paramagnetic. In addition, an interconversion between the two redox states can be achieved, both chemically and electrochemically. The functionalization of clathrochelate complexes with electron-donating groups was found to stabilize the higher oxidation states (FeIII-FeIII), which was evidenced electrochemically. However, the deliberate preparation and isolation of FeIII-FeIII complexes was not achieved. Dinuclear iron clathrochelate complexes were successfully employed as redox-active compounds for redox flow batteries, and they displayed high battery voltages and Coulombic efficiencies. Iron clathrochelate complexes are stable under the harsh conditions of metal-catalyzed coupling reactions (e.g. Suzuki or Sonogashira reactions). The high stability makes them suitable building blocks for the preparation of networks displaying permanent porosity. Both mononuclear and dinuclear iron clathrochelate-based networks displayed apparent BET surface areas between 235 and 593 m2g 1. Moreover, all clathrochelate–based porous networks displayed high thermal and chemical stabilities. Mononuclear iron clathrochelate building blocks can be decorated with chiral ligands, resulting in homochiral porous networks with apparent BET surface areas up to 548 m2g-1. Such materials were found to selectively adsorb D-tryptophan from water. Porous networks based on iron clathrochelates can also be synthesized via polycondensation reactions. This synthetic strategy involves the combination of an iron salt, a dioxime ligand, and a capping boronic acid. The resulting Fe-templated condensation reactions give networks with apparent BET surface areas up to 927 m2g-1. Similarly, these materials display high chemical and thermal stabilities. Additionally, they were found to efficiently adsorb chromium (VI) from water.