Synthesis and luminescent properties of hetero-bimetallic and hetero-trimetallic Ru()/Au() or Ir()/Au() complexes

A series of Ru( ii ) and Ir( iii ) based photoluminescent complexes were synthesised that incorporate an ancillary 2,2′-bipyridine ligand adorned with either one or two pendant N -methyl imidazolium groups. These complexes have been fully characterised by an array of spectroscopic and analytical techniques. One Ir( iii ) example was unequivocally structurally characterised in the solid state using single crystal X-ray diffraction confirming the proposed formulation and coordination sphere. These complexes were then transformed into their heterometallic, Au( i )-containing, analogues in two steps to yield either bi- or trimetallic complexes that integrate {Au(PPh 3 )} + units. X-ray diffraction was used to corroborate the solid state structure of the hetero bimetallic complex, based upon a Ru( ii )-Au( i ) species. The heterometallic complexes all displayed red photoluminescent features ( λ em = 616-629 nm) that were consistent with the parent Ru( ii ) or Ir( iii ) lumophores in each case. The modulation of the emission from the Ru( ii )-Au( i ) complexes was much more strongly evident than for the Ir( iii )-Au( i ) analogues, which is ascribed to the inherent differences in the specific triplet excited state character of the emitting states within each heterometallic species. Luminescent, heterometallic species based on [Ru-Au] 3+ , [Ru-Au 2 ] 4+ , [Ir-Au] 2+ , and [Ir-Au 2 ] 3+ .