Synthesis and photophysics of ruthenium(II) complexes with multiple pyrenylethynylene subunits

We describe the synthesis and photophysical properties of new Ru(II) complexes bearing different numbers of pyrenylethynylene substituents in either the 5 or 5,50 positions of 2,2'-bipyridine. Static and dynamic absorption and luminescence measurements reveal the nature of the lowest excited states in each molecule. The 5-substituted complexes display behavior dominated by triplet intraligand pi,pi* excited states, generating long-lived room temperature phosphorescence in the red. While the photophysical properties in the 5,5'-substituted case are still largely influenced by triplet intraligand pi,pi* excited states, the data suggest the possibility of an excited state manifold composed of mixed intraligand and charge transfer character.