Development of Photoluminescent Earth-Abundant Metal Complexes

• Darién Kercadó-Colón, Chemistry, University of Delaware

• Carsten Milsmann, Chemistry & Biochemistry, University of Delaware

Photoluminescent compounds have gained significant attention in recent years due to their wide application in digital displays, solar cells, skin treatment, and photocatalysis. Nonetheless, they have a glaring issue. The use of precious metals that tend to be up to 10x more expensive than other readily available metals creates an accessibility and economic problem for contemporary research. Facing this problem, an effort has been made to explore the use of earth-abundant metals to synthesize photoluminescent compounds. This work highlights the synthesis and characterization of  Zr, and Hf complexes via ¹H-NMR spectroscopy, electronic absorption spectroscopy, fluorescence emission spectroscopy, and single-crystal X-ray diffraction. These metal complexes employ the use of an N-heterocyclic carbene ligand in tandem with a zirconium (Zr), and hafnium (Hf) metal center.  Photophysical studies were conducted to obtain information on absorption, emission, lifetime, and quantum yield. The obtained results show that the Zr and Hf complexes had a longer lifetime than what was reported in previous literature. These results show that early transition metals can form photoluminescent compounds that exhibit long lifetimes and provide insight on how they work, which makes them a viable alternative in various applications.