Design of C^N^N type ligands and their Ir(III)-complexes to prevent deterioration pathways during the photocatalytic water reduction.
Final Report Abstract
I have worked on two different projects both including highly interesting Ir(III) luminophores. Within the first project C^N^N type ligands were employed to build up Ir(III) complexes serving as photosensitizers in the catalytic water reduction. Their coordination to Iridium was aggravated as a “flipping” of the pyridine unit occurs hindering the ligands from C^N^N coordinating behaviour. Thus, difficulties in the purification steps and losses in yield occurred. Although the turn-over numbers for hydrogen evolution could be improved by utilizing Ir(III) complexes with C^N^N ligands, the new photosensitizers did not show the expected stability which led to the decision to focus on another project. Within the second project I was working on chiral luminophores. The goal was to find synthetic pathways to endow the chromophores with e.g. liquid crystalline properties to induce long range chiral order in order to apply the metal complexes in chiral three-dimensional displays. Several ligands and neutral and charged Ir(III) complexes have been synthesized to perform functionalization reactions on them. Among these approaches were reduction, substitution or coupling reactions which gave novel insight into their behaviour concerning reactivity and stability. This knowledge will help to find further pathways to modify and optimize reactions on ligand backbones of iridium complexes that will make new classes of iridium compounds bearing unique properties accessible.
