Synthesis and OLED characteristics of isomeric phosphine oxides containing naphthoxazole moiety

Article abstract of DOI:10.1166/jnn.2017.14070

2-(2-(Diphenylphosphoryl)phenyl)naphtho[2,3-d]oxazole (2-PPN), 2-(3-(diphenylphosphoryl)phenyl) naphtho[2,3-d]oxazole (3-PPN), and 2-(4-(diphenylphosphoryl)phenyl)naphtho[2,3-d]oxazole (4-PPN) were synthesized as new light-emitting materials based on the phosphine oxide-naphthoxazole structure. The one-pot synthesis of the phosphine-naphthoxazole compound was achieved using PPA as a solvent and as a catalyst for the cyclization reaction. The phosphine structure was oxidized to phosphine oxide using aq. H₂O₂, and the chemical structures were characterized via ¹H-NMR, ¹³C-NMR, FT-IR, UV-Vis, elemental analysis (EA) and X-ray photoelectron spectroscopy (XPS). TGA under an N₂ flow shows that the PPN derivatives were thermally stable at up to 400°C. The photoluminescence (PL) spectra of the PPN derivatives in chloroform exhibited maximum wavelengths at around 439 nm for 2-PPN, 447 nm for 3-PPN, and 436 nm for 4-PPN. Electroluminescence (EL) devices with different configurations (1-4) were fabricated via vacuum deposition, and devices 1-4 emitted greenish-blue light with a maximum emission at around 509 (2-PPN), 498 (2-PPN), 528 (3-PPN) and 501 (4-PPN) nm.