A Luminescent Ruthenium Azide Complex as a Substrate for Copper-Catalyzed Click Reactions

A new ligand and its luminescent polypyridyl-Ru-II complex were synthesized and characterized. Both provide two azide functionalities in their periphery, which are electronically separated from the -system of the 2,2-bipyridine ligands by a methylene group. This azide-functionalized ruthenium complex provides access to the formerly inaccessible substrate spectrum of alkynyl-functionalized coupling substrates by using the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). Test CuAAC reactions were performed on the ligand and directly on the Ru-II complex by using phenylacetylene as a model substrate, and relatively high yields of the products were obtained under mild conditions. Transformation of the azide into the triazole had only minor influences on the photophysical properties of the polypyridyl-ruthenium core.