Bright Lanthanide~(Ⅲ) Triboluminescence despite Low Photoluminescence, and Dual Triboluminescence and Mechano-Responsive Photoluminescence

摘要

In 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 Eu~(Ⅲ)-centered PL via ligand-to-metalcharge transfer, whereas tmh provides efficient photosensitization of Tb~(Ⅲ)ions. Bright TL is observed from the Eu~(Ⅲ) and Tb~(Ⅲ) homodinuclear complexesdespite the fact that their PL quantum yields differed by a factor of >50.Nanomechanical tests reveal the ductility of the crystals, suggesting they areideal for accumulating deformation energy before breakage. Furthermore, aTL/PL color difference is observed for a Tb~(Ⅲ)/Eu~(Ⅲ) heterodinuclear complex,and grinding results in mechanochromic luminescence (MCL); this is the firstexample of a dual TL- and MCL-active lanthanide~(Ⅲ) coordination compound.The photophysical properties before, during, and after grinding are investigatedand correlated with powder and single-crystal crystallographic data.