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The syntheses, crystal structures, and detailed investigations of the photophysical properties of phosphorescent platinum(II) Schiff base complexes are presented. All of these complexes exhibit intense absorption bands with lambda(max) in the range 417-546 nm, which are assigned to states of metal-to-ligand charge-transfer ((1)MLCT) (1)[Pt(5d)-->pi*(Schiff base)] character mixed with (1)[lone pair(phenoxide)-->pi*(imine)] charge-transfer character. The platinum(II) Schiff base complexes are thermally stable, with decomposition temperatures up to 495 degrees C, and show emission lambda(max) at 541-649 nm in acetonitrile, with emission quantum yields up to 0.27. Measurements of the emission decay times in the temperature range from 130 to 1.5 K give total zero-field splitting parameters of the emitting triplet state of 14-28 cm(-1). High-performance yellow to red organic light-emitting devices (OLEDs) using these platinum(II) Schiff base complexes have been fabricated with the best efficiency up to 31 cd A(-1) and a device lifetime up to 77 000 h at 500 cd m(-2).

Solution and refinement of the crystal structure of fac-Ir(ppy) 3 is severely hampered by systematic twinning and pseudo-symmetry. fac-Ir(ppy) 3 crystallizes in the centrosymmetric space group P3 h as has been deduced from single-crystal structure refinement and investigations of the second harmonic generation (SHG) of fac-Ir(ppy) 3 powder as compared to two standard materials. The topology of the molecular packing of fac-Ir(ppy) 3 is identical to the packing observed for [Ru(bpy) 3 ] 0 , however, the site symmetry of all Ir(ppy) 3 molecules is necessarily lowered from D 3 to C 3 . Packing motifs with intermolecular "π-π interactions" of T-shaped and "shifted π stack" geometry are realized. The systematic twinning leads to the occurrence of crystalline domains with rigorously alternating chirality within the bulk of the domains but with homochiral fac-Ir(ppy) 3 contacts at the domain interfaces. These differences in packing motifs are displayed in the emission spectra and in the high-pressure-induced shifts of the emission. The emission maximum of the bulk material at 18 350 cm -1 (545 nm) and of the domain interfaces at 19 700 cm -1 (507 nm) experience for p < 25 kbar and T ) 295 K red shifts of ∆ν j/∆p ) -( 12( 2) cm -1 /kbar, and -(22 ( 4) cm -1 /kbar, respectively.