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Two new iridium(III) complexes were synthesized and fully characterized, [(bo)2Ir(pzpy)] (2a) and [(bo)2Ir(pzpyz)] (2b) (where bo = 2-phenylbenzo[d]oxazole, pzpy = 2-(1H-pyrazol-3-yl)pyridine, pzpyz = 2-(1H-pyrazol-3-yl)pyrazine). The single crystal structures of 2a-2b have been determined. Considering the relationship between their structures and photophysical properties, DFT calculations have been used to further support this inference. These Ir(III) complexes emit from the excited state of 3MLCT/3LLCT in the green and yellow region, and the quantum yields in the degassed CH2Cl2 solution at room temperature are 35.2% and 46.1%. Theoretical and experimental results show that iridium(III) complexes 2a-2b are promising phosphorescent material.

Four new cyclometalated bo-based iridium(III) complexes with different N^O ancillary ligands, [Ir(bo) 2 pic] ( 1 ), [Ir(bo) 2 prz] ( 2 ), [Ir(bo) 2 bop] ( 3 ) and [Ir(bo) 2 btp] ( 4 ) (bo = 2-phenylbenzo[d]oxazole, pic = picolinate, prz = pyrazinate, bop = 2-benzoxazol-2-yl phenol, btp = 2-benzothiazol-2-yl phenol), have been synthesized and investigated by optical spectroscopy, electrochemistry as well as density functional theory (DFT). The crystal structures of 1 , 2 and 4 have been determined, which show that each adopts the distorted octahedral coordination geometry. They exhibit intense green to orange phosphorescence ( λ max = 531–598 nm) with quantum yields of 0.19–0.94 and lifetimes of 0.078–0.468 μs in solution at 298 K. The broad range color tuning of complexes 1 – 4 is dependent on the ancillary ligand structure. The cyclic voltammetry has been measured, showing a quasireversible, metal-centered oxidation with potentials at 1.00–1.49 V. The frontier molecular orbital diagrams and the lowest-energy electronic transitions of 1 – 4 have been calculated with density functional theory (DFT) and time-dependent DFT (TD-DFT). [ABSTRACT FROM AUTHOR]

Highlights: [•] New iridium (III) complexes with 5-methyl-2-phenylbenzo[d]oxazole derivatives were synthesized. [•] The photophysical properties of the complexes were investigated in detail. [•] 5-Position methyl substitution greatly affected EL performances of the resultant complexes. [•] OLEDs based on the doped complexes showed higher EL performances. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new Ir(III) complex based on benzo[d]oxazole derivative was synthesized. [•] The photophysical and EL properties of the complex were investigated in detail. [•] The complex possessed potential application in organic electroluminescent devices. [•] Negligible efficiency roll-off was observed from heavily Ir(III)-doped device. [•] Excellent EL performances were attributed to its bulky hindrance and short lifetime. [ABSTRACT FROM AUTHOR]