Synthetic Strategies for Variably Substituted Ruthenium–Imidazophenanthrolinium Complexes

The synthesis of several symmetric and asymmetric substituted imidazophenanthrolinium ligands and their corresponding ruthenium polypyridyl complexes was achieved by applying a newly designed synthetic concept. By testing different moieties, the advantages and limits of the synthetic approach could be defined. The substitution pattern on the imidazolium moiety has no significant influence on the structural aspects of the imidazophenanthrolinium backbone or on the photophysical properties of the ruthenium compounds. Given that imidazolium salts act as precursors for N-heterocyclic carbenes, the reported results provide the basis for the design of highly efficient oligonuclear photocatalysts.