Bright Lanthanide^III Triboluminescence despite Low Photoluminescence, and Dual Triboluminescence and Mechano‐Responsive Photoluminescence

In pursuit of a new family mechanically responsive luminescent materials, it is aimed to differentiate triboluminescence (TL) from photoluminescence (PL). A β-diketonate ligand with tert-butyl groups (2,2,6,6-tetramethylheptane-3,5-dionate: tmh) selected quench EuIII-centered PL via ligand-to-metal charge transfer, whereas tmh provides efficient photosensitization TbIII ions. Bright TL observed the EuIII and homodinuclear complexes despite fact that their quantum yields differed by factor >50. Nanomechanical tests reveal ductility crystals, suggesting they are ideal for accumulating deformation energy before breakage. Furthermore, TL/PL color difference TbIII/EuIII heterodinuclear complex, grinding results in mechanochromic luminescence (MCL); this first example dual TL- MCL-active lanthanideIII coordination compound. The photophysical properties before, during, after investigated correlated powder single-crystal crystallographic data.