Photoluminescence and self-assembly of three different Eu complexes

In this study, we investigate the photoluminescence and the self-assembly of three distinct europium (Eu) complexes—[Eu(tta)$_3$(bpy)] (tris(thenoyltrifluoroacetonate)europium(III)2,2'-bipyridine), [Eu(btfa)$_3$(bpy)] (tris(4,4,4-trifluoro-1-phenyl-1,3-butanedione)europium(III)2,2'-bipyridine), and [Eu(tta)$_3$(H$_2$O)$_2$] (tris(thenoyltrifluoroacetonate)europium(III)dihydrate)—on a Au(111) surface. Utilizing scanning tunneling microscopy (STM), we explore the molecular topography and the ordered structures formed by these complexes, providing insight into their surface interactions. The europium (Eu$^{3+}$) ion, a member of the lanthanide series, is renowned for its unique photophysical properties, particularly its sharp emission bands and relatively long-lived luminescence, which make it a valuable component in light-emitting devices, bio-imaging, and sensing applications.