Effect of substituted 2,2′-bipyridine derivatives on luminescence characteristics of green emissive terbium complexes: Spectroscopic and optical analysis

Heteroleptic ternary terbium complexes with general representation as [Tb(acac)3 L] have been prepared through single step path with acetylacetone (acac) as chromophoric and substituted 2,2ꞌ-bipyridine as auxiliary (L) moieties. The synthesized complexes are characterized systematically through elemental, spectroscopic and thermogravimetric analyses. The infra-red and proton nuclear magnetic resonance spectra are consistent with the formation of complexes. Green emission is observed for the synthesized terbium complexes in solid form and in dichloromethane (DCM) solvent due to 5D4→7F5 transition. The chromaticity parameters have estimated high color purity of the complexes and their coordinates positioned in the green region of the CIE triangle. The singlet and triplet state energy of 2,2ꞌ-bipyridine (Bpy) and 2,2′-bipyridine dihydrobromide (DBr) show the efficient sensitization of Tb3+ ion in synthesized complexes by respective ligands. The bright green emission and the values of band gap indicate the utilization of synthesized complexes in the fabrication of displays.