Preparation and photoluminescent characteristics of green Tb(III) complexes with β-diketones and N donor auxiliary ligands

This paper presents four octa coordinated ternary terbium complexes based on 2-benzoylacetophenone (BAP) and other auxiliary ligands. For characterization purpose, elemental analysis, electrochemical study, thermal analysis and spectroscopic investigations were carried out in detail. Optical band gap (3–4 eV) of complexes was determined from Tauc’s relation. Upon excitation in UV region, emission spectra of complexes demonstrate peaks of Tb3+ ion at ∼616 nm, 589 nm, 548 nm, and 492 nm, attributed to 5D4 → 7FJ (J = 3 to 6) respectively due to energy transfer from ligand to Tb(III) ion via antenna effect. Peak at 548 nm corresponding to 5D4 → 7F5 is responsible for bright green emission of synthesized terbium complexes. CIE color coordinates and color purity further corroborate the green emission of Tb3+ complexes. The complexes were found to be quite stable as studied by thermal analysis. The outcomes of characterizations have demonstrated that these complexes could behave as good contenders in lighting systems and displays owing to their photometric characteristics.