Triboluminescence and crystal structures of europium(III) complexes

The triboluminescence of four europium complexes [Eu(TTA)4]Y (TTA: 2-thenoyltrifluoroacetone; complex 1, Y1: 1,2-dimethylpyridinium; complex 2, Y2: 1,2,6-trimethylpyridinium; complex 3, Y3: N-methylisoquinolium; complex 4, Y4: 4-aminopyridinium) was observed. The triboluminescent spectra of 1–4 and the crystal structures of 1, 3 and 4 were determined. The triboluminescence maxima are all similar to those of their photoluminescence, indicating identical emitting species. The triboluminescent activity of 1 may be correlated with its non-centrosymmetric space group. The disorder of the thienyl rings and CF3 groups in centrosymmetric 3 and 4 may be responsible for their triboluminescent activities.