Efficient 0.4 μm–1.6 μm emission from muffin-shaped nine-coordinated ternary samarium( iii ) and erbium( iii ) complexes

coordination sphere. Hirshfeld surface analysis reveals the presence of different non-covalent interactions (NCIs) and their role in stabilizing the molecular structure. The optical properties of Sm1 and Er1 were analysed and discussed in detail using UV-Vis-NIR absorption, steady-state emission and excited-state decay dynamics. Upon ligand-centred excitation, either in the solid state or in solution, Sm1 and Er1 exhibit their typical f-f emissions, covering a wide range of 400-1600 nm. Both complexes display a sizeable excited lifetime and fall in the category of efficient lanthanide materials. A possible emission mechanism involved in the sensitized visible and NIR emission is also proposed based on the available data set.