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.