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

Abstract

Absorption and emission spectra and mean lifetimes (τm) 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 (τm = 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 (τm = 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.