Synthesis and Characterization of Phenanthrylphosphine Gold Complex:  Observation of Au-Induced Blue-Green Phosphorescence at Room Temperature

A new 9-diphenylphosphinophenanthrene ligand (9DPP, 1), its oxide (9DPPO, 2), and its gold complex [(AuCl(9DPP)] (3) were synthesized. The Au(I) complex 3 was found to exhibit intense blue-green, room-temperature phosphorescence (Φ_p = 0.06 and τ_T = 22.7 μs) originating in the locally excited triplet of the phenanthrene moiety (³LE) in degassed 2-methyltetrahydrofuran solution. On the assumption that Φ_ST = 1.0 for 3, the radiative rate constant (k_r ) in the triplet state is calculated to be 2.6 × 10³ s^-1. This value is 4 orders of magnitude larger than the radiative rate constant of the triplet phenanthrene (0.26 s^-1). Thus, the coordinated Au(I) atom is concluded to have a markedly large heavy-atom effect on k_r of the phenanthrene chromophore in 3.