Inorganic photophysics in solution. Part 3.—Temperature activation of decay processes in the luminescence of tris(2,2′-bipyridine)osmium(II) and tris(1,10-phenanthroline)osmium(II) ions

Abstract

The behaviour of (i) the luminescence spectrum, (ii) the (relative) luminescence quantum yield and (iii) the luminescence lifetime of [Os(phen)₃]²⁺(phen = 1,10-phenanthroline) and [with respect to (ii) and (iii)] of [Os(bipy)₃]²⁺(bipy = 2,2′-bipyridine), has been examined in the temperature range 77–300 K, principally in 9 mol dm^–3 LiCl + H₂O and LiCl + D₂O, but also in cellulose acetate film. Two principal routes provide the deactivation of the excited state: (i) a non-radiative pathway of high energy (≈ 13 kJ mol^–1 in LiCl + H₂O and LiCl + D₂O, and 6–7 kJ mol^–1 in cellulose acetate) and (ii) what is probably a radiative pathway of energy ≈ 0.7 kJ mol^–1(60 cm^–1) in all media.