Er3+ and Eu3+ complexes with heptafluoroacetylacetone and tris(pentafluoro)phenylphosphine oxide: The role of the pentafluorophenyl group on the coordination geometry and on the electronic absorption spectra

► Er3+ and Eu3+ complexes with fluorinated ligands. ► Coordination geometry controlled by C-F···π interactions of the fluorinated ligands. ► The π system of the acac-F7 ligands is the origin of the antenna behaviour.