Phosphorescent Iridium(III) Cyclometalates Supported by 2‐(1,2‐Dihydronaphthalen‐4‐yl)pyridine Ligand

摘要

Novel Ir(III) cyclometalates, (dnpy) 2Ir(acac) (2) and faca??Ir(dnpy)3 (3), supported by 2a??(1,2a??dihydronaphthalena??4a??yl)pyridyl ligand (dnpy) were synthesized and characterized. Xa??ray diffraction study on 3 revealed facial arrangement of three dnpy ligands around the Ir center. Photoluminescence (PL) spectra of 2 exhibited orange emission centered at 590a??nm, which is almost similar to that observed for 2a??naphthylpyridine complex, (napy) 2Ir(acac) ( III ). In contrast, compound 3 displayed bluea??shifted, yellow emission at 550a??nm. Trisa??complex 3 showed higher quantum efficiencies than 2 in both the solution and film states. Cyclic voltammetry measurements indicated that replacing naphthyl with 1,2a??dihydronaphthyl ring raises both the metala??centered HOMO level and liganda??centered LUMO level in 2 and 3. It was suggested that 1,2a??dihydronaphthyl ring has a stronger electrona??donating effect than naphthyl ring, while the ??* orbital of dnpy ligand is less stabilized due to partial conjugation of the dihydronaphthyl ring.