Mononuclear luminous β-diketonate Ln(III) complexes with heteroaromatic auxiliary ligands: synthesis and luminescence characteristics.

A series of lanthanide (samarium and terbium) β-diketonates with heteroaromatic auxiliary ligands was synthesized. The prepared complexes were characterized through electrochemical, thermal, and spectroscopic analyses. Infrared analysis revealed the binding of the respective metal ion to oxygen and nitrogen atoms of diketone and ancillary ligands. Thermogravimetry/differential thermogravimetry profiles provided thermal information and specified the high thermal stability of the prepared complexes. The complexes exhibited the sharp and structured Ln-based emission in the visible region upon irradiation in the ultraviolet range. Photophysical analysis demonstrated the green and orange-red emission due to the respective characteristic transitions of Tb 3+ and Sm 3+ ions. Photophysical properties affirmed the luminous behaviour of the synthesized complexes. These luminous lanthanide complexes could be used as emitting materials in the design of organic light-emitting diodes.