Multimetallic and Mixed Environment Iridium(III) Complexes: A Modular Approach to Luminescence Tuning Using a Host Platform

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.