Terbium(III) complexes sensitized with β-diketone and ancillary ligands: Synthesis, elucidation of photoluminescence properties and mechanism

Abstract

A β-diketone 1-(2-hydroxyphenyl)-3-phenylpropane-1,3-dione (HHPPP) has been used to synthesize binary and ternary terbium(III) complexes of the form Tb(HPPP)L [where L = H2O (C1), 1,10-phenanthroline (C2), 2,2′-bipyridyl (C3), 2,2′-biquinoline (C4) and neocuproine (C5)]. These complexes are characterized by various techniques including IR, 1H-NMR, elemental analyses, powder XRD, TG–DTG, UV–visible and photoluminescene spectroscopy. The emission spectra of complexes exhibit characteristics bands of terbium(III) ion with 5D4 → 7F5 (545 nm) as the most prominent band. The photophysical properties clearly reveal that the substitution of solvent molecules by anciliary ligands essentially increases the luminescence intensity and decay time of ternary complexes, suggesting the sensitization of Tb(III) ion by both HPPP and anciliary ligands. The sensitization process in complexes is also delineated by proposed energy transfer mechanism. The color coordinates of the complexes fall under green region of Commission Internationale de L’Eclairage diagram. These results demonstrate that luminescent terbium(III) complexes could be a deserving component for organic light emitting diodes and display devices.