Diverse Coordination Numbers and Geometries in Pyridyl Adducts of Lanthanide(III) Complexes Based on β-Diketonate

Abstract

Ten mononuclear rare earth complexes of formula [La(btfa)3(H2O)2] (1), [La(btfa)3(4,4′-Mt2bipy)] (2), [La(btfa)3(4,4′-Me2bipy)2] (3), [La(btfa)3(5,5′-Me2bipy)2] (4), [La(btfa)3(terpy)] (5), [La(btfa)3(phen)(EtOH)] (6), [La(btfa)3(4,4′-Me2bipy)(EtOH)] (7), [La(btfa)3(2-benzpy)(MeOH)] (8), [Tb(btfa)3(4,4′-Me2bipy)] (9) and (Hpy)[Eu(btfa)4] (10), where btfa = 4,4,4-trifuoro-1-phenylbutane-1,3-dionato anion, 4,4′-Mt2bipy = 4,4′-dimethoxy-2,2′-bipyridine, 4,4′-Me2bipy = 4,4′-dimethyl-2,2′-bipyridine, 5,5′-Me2bipy = 5,5′-dimethyl-2,2′-bipyridine, terpy = 2,2′:6′,2′-terpyridine, phen = 1,10-phenathroline, 2-benzpy = 2-(2-pyridyl)benzimidazole, Hpy = pyridiniumH+ cation) have been synthesized and structurally characterized. The complexes display coordination numbers (CN) eight for 1, 2, 9, 10, nine for 5, 6, 7, 8 and ten for 3 and 4. The solid-state luminescence spectra of Tb-9 and Eu-10 complexes showed the same characteristic bands predicted from the Tb(III) and Eu(III) ions. The Overall Quantum Yield measured (ϕTOT) at the excitation wavelength of 371 nm for both compounds yielded 1.04% for 9 and up to 34.56% for 10.

Keywords

• lanthanum(III)
• terbium(III)
• europium(III)
• β-diketonate anion
• luminescence
• crystal structure