Photophysics of heteropolynuclear complexes containing ruthenium and osmium tris(bipyridine) and platinum diimine bis(acetylide)

The study of photoinduced processes in multi-chromophoric complexes is of particular interest both for mimicking natural photosynthesis and for making molecular-scale electronic devices. As units for these systems, polypyridine complexes of d6 metals such as Ru(II) and Os(II) have been the most studied in the past decades, while interest in the properties of d8 Pt(II) complexes of the type (diimine)PtL2, where L is an anionic ligand, has increased in recent years. Although relatively few reports on the photophysical properties of (diimine)PtL2 complexes where L is an arylacetylide are present in the literature, the ability of their luminescent 3MLCT excited state in transfering energy or accepting electrons has been demonstrated in various systems. To the best of our knowledge diimine Pt(II) bis(acetylide) complexes have never been combined with tris(bipyridine) units of Ru(II) and Os(II), and we intended to study this new type of heteropolynuclear systems in view of exploring their photoactivity. We herein report on the photophysical properties of newly synthesized complexes consisting of a [Pt(dbbpy)(C-C(bpy)Ru(bpy)2) (C-C(bpy)Os(bpy)2)]4+ triad (Figure 1) and of reference mononuclear and binuclear models.