Bright LanthanideIII Triboluminescence despite Low Photoluminescence, and Dual Triboluminescence and Mechano‐Responsive Photoluminescence

Abstract

AbstractIn pursuit of a new family of 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) is selected to quench EuIII‐centered PL via ligand‐to‐metal charge transfer, whereas tmh provides efficient photosensitization of TbIII ions. Bright TL is observed from the EuIII and TbIII homodinuclear complexes despite the fact that their PL quantum yields differed by a factor of >50. Nanomechanical tests reveal the ductility of the crystals, suggesting they are ideal for accumulating deformation energy before breakage. Furthermore, a TL/PL color difference is observed for a TbIII/EuIII heterodinuclear complex, and grinding results in mechanochromic luminescence (MCL); this is the first example of a dual TL‐ and MCL‐active lanthanideIII coordination compound. The photophysical properties before, during, and after grinding are investigated and correlated with powder and single‐crystal crystallographic data.