Luminescence of Ln(III) dithiocarbamate complexes (Ln = La, Pr, Sm, Eu, Gd, Tb, Dy)

We have discovered room temperature photoluminescence in SM3+ and Pr3+ dithiocarbamate complexes. Surprisingly, these complexes exhibit more intense emission than those of the Eu3+, Tb3+, and Dy3+ analogues. The electronic absorption, excitation, and emission spectra are reported for the complexes [Ln(S2CNR2)(3)L] and NH2Et2[Ln(S2CNEt2)(4)], where Ln = Sm, Pr; R = ethyl, butyl, benzyl; and L = 1,10-phenanthroline, 2,2'-bipyridine, and 5-chloro-1,10-phenanthroline. The lowest ligand-localized triplet energy level (T-1) of the complexes are determined from the phosphorescence spectra of analogous La3+ and Gd3+ chelates. The luminescence decay curves were measured to determine the excited-state lifetimes for the Pr3+ and Sm3+ complexes. X-ray crystal structures of Sm((S2CNBu2)-Bu-i)(3)phen, Pr(S2CNEt2)(3)phen, and Pr((S2CNBu2)-Bu-i)(3)phen are also reported.