Visible and NIR emitting Yb(iii) and Er(iii) complexes sensitized by β-diketonates and phenanthroline derivatives

Abstract

Five new complexes namely, [Er(bta)₃(me-phen)] (1), [Yb(bta)₃(me-phen)] (2), [Gd(bta)3(me-phen)] (3), [Yb(bta)₃(pyz-phen)] (4), and [Er(tta)₃(pyz-phen)] (5) have been prepared with the fluorinated β-diketone ligands Hbta and Htta (Hbta = benzoyltrifluoroacetone and Htta = 2-thenoyltrifluoroacetone) combined with the azacyclo phenanthroline-derivatives, 5-methyl-1,10-phenanthroline (me-phen) and pyrazino[2,3-f][1,10]phenanthroline (pyz-phen). The crystal structures of 2, 4 and 5 have been solved by single-crystal X-ray diffraction. PXRD patterns show that 1–3 are isostructural. All the compounds exhibit a molecular structure with the metal atom in an eight-coordination geometry. The photophysical processes involved in the photoluminescence of the complexes are investigated; as a result, the radiative lifetimes (τ_Ln), the 4f–4f emission quantum efficiencies (Φ_Ln) and the energy-levels diagram are calculated.