Multi-functional organosamarium complexes, photometric properties, applications, and energy transfer process: a review

The exploration of sustainable luminescent compounds has increased economically and globally in recent decades. In this regard, organosamarium complexes have emerged as outstanding luminescent sources in various branches like lighting systems, bio-assays, magnets, organic light-emitting diodes, bioimaging, and material design because of their enhanced optical and thermal features. In this article, we will explore the synthesis, properties, and applications of mononuclear, dinuclear, and polynuclear organosamarium complexes and their luminescence enrichment. The combination of Sm(III) ion with a diversity of organic ligands consisting of hetero-donor atoms and an extensive π-conjugation backbone may prove an effective strategy for designing highly stable complexes. This type of grouping will lead to efficient energy transfer from the coordinated organic ligand via indirectly populating the Sm(III) emitting state. The Sm(III) complexes show emission bands in the visible region at ~ 564, 600, and 646 nm, arising from ⁴G_5/2 → ⁶H_5/2, ⁶H_7/2, and ⁶H_9/2 transitions, respectively. This review paper attempts to furnish an in-depth analysis and highlight the significant outcomes of the recently published organosamarium complexes. Lastly, the key challenges and future perspectives for the design and development of organosamarium complexes in various applications are provided in this review.