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 (Φp = 0.06 and
τT = 22.7 μs) originating in the locally excited triplet of the
phenanthrene moiety (3LE) in degassed 2-methyltetrahydrofuran
solution. On the assumption that ΦST = 1.0 for 3, the radiative
rate constant (kr ) 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 kr of the phenanthrene chromophore in 3.