Synthesis, characterization and color-purity near-infrared (NIR; λ em=780 nm) phosphorescence of one C 1-symmetric [Ir(C"N)2(N"O)]-bis-heteroleptic Ir(III)-complex

In sharp contrast to the success of Ir(III)-complex-based visible-phosphors, the molecular design of their efficient NIR-emissive counter-parts, as constrained by the so-called "energy gap law", is distinctively difficult. Especially, it remains a great challenge to develop new Ir(III)-complex-based phosphors with both efficient and color-purity NIR-emission. Herein, based on the molecular design of [Ir(dpbq)2(L)], the highly conjugated HC"N-main ligand Hdpbq renders the desirable color-purity NIR-phosphorescence (lambda PL = 780 nm), and the electron-rich while N"OH-ancillary HL is beneficial to augmented 3MLCT effect and large transition dipole moment (TDM). Accordingly, its color-purity NIR-phosphorescent efficiency (Phi PL = 3.9 %) is significantly higher than those (Phi PL = 1.9-2.5 %) of the [Ir(dpbq)2(O"O)]-analogue.