Lanthanide ions are renowned for their unique magnetic and luminescent properties, which originate from their discrete electronic energy levels. The intricate relationship between these energy states and the local coordination environment can be deciphered through resolved luminescence spectroscopy,¹ making it a powerful tool to track the behavior of coordination complexes. This approach enables the rational design of these species to enhance luminescence properties, tailor emission profiles, or exploit their sensitivity to changes in their environment.²

Over the past decade, Circularly Polarized Luminescence (CPL) from chiral lanthanide complexes has experienced renewed interest, driven by potential applications such as novel bioprobes for microscopy or optimized dyes for OLED displays. However, the precise characterization of CPL properties remains a challenge. In this presentation, we will explore key strategies for accessing CPL-active lanthanide chromophores, from ligand design to chirality induction. We will also address the methodological hurdles in measuring and interpreting CPL properties, which complicate straightforward comparisons of reported structures and precise determination of dissymmetry factors (g_lum) for each electronic transition.^3,4

Beyond their luminescence properties, we will also discuss how such heavy-element complexes are finding emerging applications in the field of structural biology.

_{1.   In Handbook on the Physics and Chemistry of Rare Earths, Elsevier, 2025, 67:37.}

₂.   _{CM Balogh, I N’Dala-Louika, I Suleimanov, A Pons, M Jouffrieau, C Camp, F Chaput, L Veyre, C Thieuleux, O Maury and F Riobé, Adv. Opt. Mater., 2024, 12:2400091.}

₃.   _{A Sickinger, B Baguenard, A Bensalah-Ledoux, Y Guyot, L Guy, F Pointillart, O Cador, M Grasser, BL Guennic, F. Riobé, O Maury and S Guy, J. Mater. Chem. C, 2024, 12:4253.}

₄.   _{A Sickinger, M Grasser, B Baguenard, A Bensalah-Ledoux, L Guy, AT Bui, Y Guyot, V Dorcet, F Pointillart, O Cador, S. Guy, O Maury, BL Guennic and F Riobé, Phys. Chem. Chem. Phys., 2024, 26:15776.}