TD-DFT Studies on Electronic and Spectral Properties of Platinum(II) Complexes with Phenol and Pyridine Groups

The molecular structures of the ground and the lowest triplet states for a series of Pt(II) complexes PtLCl(1)[L=6-(2-hydroxyphenyl)-2,2'-bipyridine], Pt(pp)(2)[pp=2-(2-hydroxyphenyl)pyridine](2), PtbpyCl(2)(bpy=2,2'-bipyridine)(3), and the free tridentate L ligand(4) were optimized by the density functional theory B3LYP and UB3LYP methods, respectively. On the basis of optimized geometries, the spectral properties were investigated with time-dependent density functional theory(TD-DFT). In comparison with those of complexes 2 and 3, the more rigid structure of complex 1 together with its low rate of the radiationless decay via nonemissive d-d state leads to higher photoluminescence quantum efficiency. And the phosphorescence quantum efficiency of complex 1 can be easily controlled by modifying auxiliary ligands. The introduction of fluorine ligand into complexes can effectively increase the radiation transition rate and decrease the radiationless d-d transition rate, and as a result, a novel complex PtLF(5) might be a good phosphorescent material suitable for organic electronic devices.