Rare Earth Acylpyrazolonates-Synthesis, Structure, Luminescent Properties and Applications

Acylpyrazolonate derivatives of rare earth elements (REE), being a non-mainstream class of β-diketonates, have continued to attract chemists and materials scientists for more than half a century. The electronic structure features of these ligands make them effective sensitizers of the luminescence of various lanthanides, emitting in the visible and IR regions. Exhibiting all the typical structural types of β-diketonates, acylpyrazolonates can form heterometallic complexes with d-elements due to the presence of additional donor atoms. The review covers more than half a century of the history of these compounds and provides a perspective on the development of this class of compounds and their transformation into materials of the 21st century.