Enhancement in photophysical properties of octacoordinated Dy(III) complexes via energy transfer from photosensitizing ligands

In this study, β-diketone (1,1,1-trifluoroacetylacetone, tfaa) based mononuclear anhydrous octacoordinated dysprosium complexes i.e. [Dy(tfaa)3(TOPO)2] (D1), [Dy(tfaa)3(phen)] (D2), [Dy(tfaa)3(NeoC)] (D3) and [Dy(tfaa)3(BathoC)] (D4) were synthesized using four different neutral ligands. The effect of different sensitizers on Dy(III) ion is analyzed using various spectroscopic and analytical techniques. The composition and bonding were examined by elemental analysis, infrared spectroscopy, NMR spectroscopy and thermal analysis (TGA). The luminescent characteristics of the synthesized complexes were further investigated. The complexes, when exposed to UV light, displayed characteristic emissions of the central Dy(III) ion. The photoluminescence spectra indicated the strongest emission intensity of D3 complex. The hyper-intense transition in all complexes is sensitive to the metal ion environment. The semiconducting nature of complexes was confirmed by optical and electronic band gap values obtained from absorption spectroscopy and cyclic voltammetric analysis, respectively. The neutral ligands (TOPO, phen and its derivatives) along with tfaa, are found to be good sensitizers for trivalent dysprosium ion. All the characteristic features of these prepared complexes show their potential applications in the fabrication of OLEDs.