Luminescence from Transition-Metal Complexes: Tris(2,2′-bipyridine)- and Tris(1,10-phenanthroline)Ruthenium(II)

Abstract

Absorption and emission spectra and mean lifetimes (τ_m) of the luminescence of tris(2,2′‐bipyridine)‐ and tris(1,10‐phenanthroline)ruthenium(II) are reported. For the 2,2′‐bipyridine complex, two weak absorption bands occurring at 15 050 and 18 550 cm⁻¹ are assigned, respectively, to the ¹A₁→³T₁ and ¹A₁→¹T₁ transitions of d—d type, and the intense luminescence with origin at 17 250 cm⁻¹ (τ_m = 5.92 μsec) is assigned to ¹T₁→¹A₁ fluorescence. For the 1,10‐phenanthroline complex, no intra‐d transitions were observed in absorption, but the bright luminescence with origin at 17 700 cm⁻¹ (τ_m = 9.93 μsec) was assigned to ¹T₁→¹A₁ fluorescence in analogy with the first compound. The energy levels are analyzed on the basis of an octahedral model, and empirical values for the Racah B and C parameters for Ru II and the crystal‐field parameter Δ are evaluated. Possible uses of the compounds for laser applications are suggested.