Syntheses, Crystal Structures and Photophysical Properties of a Blue Phosphorescent Iridiume Pyrimidine Complex

An iridium(III) complex of Ir(N4) (MDFPPM)(2) [MDFPPM=2-(2,4-difluorophenyl)-4,6-dimethylpyrimidine, N4=5-(2-Pridyl)-1H-tetrazole] has been prepared, and characterized by X-ray single crystal diffraction. The photophysical properties and energy-level structure of Ir(N4)(MDFPPM)(2) are studied by ultraviolet-visble (UV-Vis) absorption, fluorescence, cyclic voltammetry (CV), and time-dependent density functional theory (TD-DFT) calculation. X-ray diffraction studies have revealed that the complex belongs to monoclinic system with space group of P2(1)/c. A theoretical calculation reveals that the HOMO of Ir(N4)(MDFPPM)(2) is mainly distributed on the iridium ion and the phenyl group of the cyclometalated ligand MDFPPM, while the LUMO is mainly centered on the pyrimidine group of the cyclometalated ligand MDFPPM. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMQ) levels of Ir(N4)(MDFPPM)(2) are -5.98 and -3.22 eV, respectively. The complex of Ir(N4)(MDFPPM)(2) exhibits blue phosphorescent emission with a peak at 449, 480 and 513 nm in acetonitrile solution at 77 K, and with International Commission on Illumination (CIE) Coordinates of (0.15, 0.23). CCDC: 1043237, Ir(N4)(MDFPPM)(2); 1043238, Ir(N4)(MDFPPM)(2)center dot CH2Cl2.