Two isostructural triboluminescent lanthanide complexes

(4‐Di­methyl­amino­pyridine)­tris(2,2,6,6‐tetra­methyl­heptane‐3,5‐dionato)­terbium(III), [Tb(C₁₁H₁₉O₂)₃(C₇H₁₀N₂)], and its samarium analogue, [Sm(C₁₁H₁₉O₂)₃(C₇H₁₀N₂)], are isostructural. Their polar space group is consistent with observed second harmonic generation and with the involvement of piezoelectric charging in their intense triboluminescence properties, which are of interest for the development of damage sensors in composite materials. The metals display irregular seven‐coordination by one substituted pyridine and three chelating diketonate ligands, bond lengths to Tb being shorter than those to Sm.