Abstract
Mononuclear and trinuclear bis-cyclometallated Ir(III) complexes of the host ligands tris(4-[4'-methyl-2,2'-bipyridyl]methyl)cyclotriguaiacylene (L1) and tris(4-(4'-methyl-2,2'- bipyridyl)carboxy)cyclotriguaiacylene (L2) have been prepared. Complexes [{Ir(ppy)(2) }(3) (L1)](PF(6) )(3) (1.1), [{Ir(ppy)(2) }(L1)](PF(6) )(3) (1.2), [{Ir(ppy)(2) }(3) (L2)](PF(6) )(3) (2.1) and [{Ir(ppy)(2) }(L2)](PF(6) )(3) (2.2) (where ppy=phenylpyridinato) showed distinct photophysical properties depending on the L ligand. Complexes featuring the L1 ligand were comparatively blue-shifted in solution, with longer lifetimes and higher quantum yields. The mixed bis-cyclometallated Ir(III) complexes [{Ir(ppy)(2) }{Ir(dFppy)(2) }(2) (L1)](PF(6) )(3) (1.3), [{Ir(ppy)(2) }{Ir(dFppy)(2) }(2) (L2)](PF(6) )(3) (2.3), [{Ir(ppy)(2) }(2) {Ir(dFppy)(2) }(L1)](PF(6) )(3) (1.4) and [{Ir(ppy)(2) }(2) {Ir(dFppy)(2) }(L2)](PF(6) )(3) (2.4) (where dFppy=2,4-difluorophenylpyrinato) were also synthesised. Steady-state and time-resolved spectroscopy, along with electrochemical investigations, show that the Ir(III) chromophores within these mixed Ir-environment species behave as isolated centres, with no energy transfer or electronic communication between them.