Synthesis, characterization and electroluminescence of B(III) compounds: BPh2(2-(2-quinolyl)naphtho[b]imidazolato) and BPh2(2-(2-quinolyl)benzimidazolato)

Two novel luminescent boron compounds, BPh2(2-(2-quinolyl)naphtho[b]imidazolato) (1) and BPh2(2-(2-quinolyl)benzimidazolato) (2), have been synthesized by the reactions of triphenylboron with appropriate ligands, 2-(2-quinolyl)naphtho[b]imidazole (QNI) and 2-(2-quinolyl)benzimidazole (QBI), respectively. The structure of 1 was determined by single crystal X-ray diffraction, while 2 by spectroscopic methods. The structure of 1 reveals that the boron center is four coordinated. Several types of OLED possessing different colors were fabricated by using 1 as emitter. For the three-layer OLED with the structure ITO/NPB/2/Alq3/Mg–Ag, an emission band covering the whole visible region from 400 to 750 nm with the maximum brightness of 320 cd/m2 was observed, indicating a perfect white light OLED (CIE = 0.33, 0.37). Compounds 1 and 2 form a new family of organometallic emitting materials which could be of interest for practical application.