Effect of second ligand on the luminescence of Samarium (III) dibenzoylmethane complexes: Syntheses, crystal structures, thermal analysis and luminescence study

Abstract

The ternary complexes of Sm(III) with dibenzoylmethane (dbm) were synthesized by introducing 1,10-phenanthroline (phen), 4,7-dimethyl-1,10-phenanthroline (dmphen), 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen), 4,7-diphenyl-1,10-phenanthroline (dpphen), 2,2-bipyridyl (bpy), 4,4’-dimethyl-2,2-bipyridyl (4,4-dmbpy), 5,5’-dimethyl-2,2-bipyridyl (5,5-dmbpy) and 4,4’-di-tert-butyl-2,2-bipyridyl (4,4-dtbbpy) as a second ligand. The complexes were isolated and characterized by elemental analysis (CHN), thermogravimetric analysis (TGA), IR spectroscopy, luminescence spectroscopy and single crystal X-ray diffraction. Structural study shows that in all complexes Sm(III) is in square antiprism geometry. All complexes emit strong luminescence under ultraviolet excitation. The strongest emission is at 643 nm which can be assigned for 4 G 5/2 to 6 H 9/2 transition, equivalent to energy of 15550 cm−1. The addition of the second ligand has increased the emission intensity of the complexes while the transition is maintained. Luminescence studies show that under excitation of 418 nm, all Sm(III) ternary complexes emit orange luminescence and the strongest emission for all complexes is at 643 nm (15521 cm−1) which can be assigned to 4G5/2 to 6H9/2 transition.