Green–Emitting Terbium(III) Complexes With Tunable Optoelectronic Properties Enabled by Functionalized Bipyridine Ligands

ABSTRACT

Four new heteroleptic terbium(III) complexes of general composition [Tb(tfpd) ₃ N] were synthesized via a facile one pot approach using 4,4,4‐trifluoro‐1‐phenyl‐1,3‐butanedione (tfpd) as the β‐diketonate ligand and substituted 2,2′‐bipyridine derivatives as ancillary co‐ligands. Elemental (CHN) analysis, along with FT‐IR and NMR spectroscopy, confirmed the formation of stable eight‐coordinate Tb ³⁺ complexes involving O, O– and N, N– donor coordination. The compounds exhibit wide optical band gaps, indicating semiconducting behavior and show good thermal stability, as evidenced by thermogravimetric analysis. Photoluminescence studies reveal Tb ³⁺ ‐centered green emission governed by the ⁵ D ₄  →  ⁷ F ₅ transition at 547 nm. CIE chromaticity coordinates confirm bright green emission for complexes E1–E3, whereas E4 shows a slight blue shift due to ligand centered contributions. The results show that varying ancillary ligands effectively tunes the structural and photophysical properties of Tb(III) complexes, highlighting their potential for optoelectronic and display applications.