Postfunctionalization of luminescent bipyridine Pt II bisacetylides by click chemistry

The synthesis of a family of differently substituted 5- and 4,4′-ethynyl-bpy Pt II bisacetylide complexes (bpy = 2,2′-bipyridine) and their postfunctionalization using click chemistry is described. Cu I-catalyzed azide-alkyne [3+2] cycloaddition was an efficient method to decorate the Pt II complexes with a manifold of moieties in high yields. The absorption and emission properties and the electrochemical behaviour of all of the complexes have been investigated. The studied compounds emit at room temperature between 598 and 660 nm, reaching photoluminescence quantum yields of 0.33 in solution. The bright luminescent properties of the unsubstituted bpy Pt II bisacetylide complex remained unaffected upon click-functionalization as the resulting triazole substituent has no significant influence on the nonradiative decay rate constant. This route opens new possibilities for to control the bulk of the complexes, their solubility, and their further extension or immobilization on macromolecules, polymers and surfaces without affecting their intrinsic properties. Two derivatives were selected as triplet emitter molecules in solution-processed polymer-based organic light-emitting devices.