RESUMEN
Pd(0) complexes with monodentate phosphine ligands, [Pd(P)n] (n = 3, 4), are well-known catalysts. However, the nature of the Pd(0) complex, especially the basic photophysical properties of the Pd(0) complexes, has not been extensively explored. In this work, we measured the general photophysical properties and crystal structures of Pd(0)-bearing PPh3 derivatives in the solid state and in solution. In the solid state, four-coordinated Pd(0) complexes exhibited blue-yellow emission. On the other hand, three-coordinated Pd(0) complexes displayed yellow-orange emission. In solution, orange emission of three-coordinated complexes was observed, and prompt fluorescence was detected using time-resolved emission spectroscopy, which suggests a thermally activated delayed fluorescence mechanism. Density functional theory (DFT) and time-dependent DFT calculations show that the difference in the transition mechanism between the [Pd(PPh3)4] and [Pd(PPh3)3] complexes explains the different emission colors. The emitting states of both complexes have metal-to-ligand charge-transfer character, but the metal-centered d â p transition is considerably incorporated for emission of the tris complex.
RESUMEN
We report the synthesis and photophysical properties of Cu(i) complexes with 1,10-phenanthroline (phen) and monodentate phosphine ligands. Single crystal X-ray structural analysis revealed that these have three-coordinated trigonal planar geometries. We also found that one of them, [Cu(phen)(Johnphos)]BF4 (Johnphos = 2-(di-tert-butylphosphino)biphenyl), is considerably emissive both in solution and solid states. The emission maximum wavelength of the emission of the complex is 580 nm, and the lifetime of the emission is 2 µs in solution. Moreover, we have systematically investigated the photophysical and redox properties of four-coordinate complexes [Cu(NN)(P)2]+ in addition to three-coordinate complexes [Cu(NN)(P)]+. Charge transfer transitions play a key role in the photophysics of these complexes.