Pressure dependence of Pt(2,2′-bipyridine)Cl2 luminescence. The red complex converts to a yellow form at 17.5 kbar

The luminescence of the red (linear-chain) form of Pt(bpy)Cl2 (bpy=2,2′-bipyridine) has been measured as a function of hydrostatic pressure up to 30 kbar. The luminescence band maximum is red-shifted (158 cm−1/kbar), and the intrachain Pt(II)–Pt(II) distance decreases from 3.45 to 3.25 Å, between ambient pressure and 17.5 kbar. Strong discontinuities in the emission energy, bandwidth, and intensity at 17.5 kbar are interpreted in terms of a crystallographic phase transition from the red to a yellow form of Pt(bpy)Cl2.