Slow magnetic relaxation and luminescence properties in neodymium(iii)-4,4,4-trifluoro-1-(2-naphthyl)butane-1,3-dionato complexes incorporating bipyridyl ligands

Five new eight-coordinated Nd(iii) mononuclear complexes with the formulae [Nd(ntfa)3(EtOH)2] (1), [Nd(ntfa)3(phen)] (2), [Nd(ntfa)3(bipy)] (3), [Nd(ntfa)3(5,5′-Me2bipy)] (4) and [Nd(ntfa)3(4,4′-Mt2bipy)] (5), where ntfa = 4,4,4-trifluoro-1-(naphthalen-2-yl)butane-1,3-dionate, phen = phenanthroline, bipy = 2,2′-dipyridine, 5,5′-Me2bipy = 5,5′-dimethyl-2,2′-dipyridine, and 4,4′-Mt2bipy = 4,4′-dimethoxy-2,2′-dipyridine, were synthesized and structurally characterized. Magnetic measurements were carried out on complexes 2-5. Dynamic magnetic studies revealed single-molecule magnet (SMM) behavior for complexes 2, 4 and 5 with anisotropy energy barriers and preexponential factors of Ueff = 18 cm-1, τ0 = 2.2 × 10-7 s; Ueff = 31 cm-1, τ0 = 1.0 × 10-9 s and Ueff = 19 cm-1, τ0 = 8.7 × 10-8 s, respectively. The ancillary chelating bipyridyl ligands in complexes 2-5 greatly enhance the solid state luminescence emission in the visible and NIR regions through efficient energy transfer from the ligands to the central Nd3+ ion. This study highlights the bifunctionality of the Nd(iii) complexes.