Pressure-Induced Blue-Shifted and Enhanced Emission: A Cooperative Effect between Aggregation-Induced Emission and Energy-Transfer Suppression

Most
organic piezochromic materials exhibit red-shifted and quenched
emission as pressure increases. However, an abnormal phenomenon of
pressure-induced blue-shifted and enhanced emission is observed in
a 9-(3-(1,2,2-triphenylvinyl)­phenyl)­anthracene crystal, which is based
on discrete π–π anthracene (AN) dimers stacking
with tetraphenyl­ethylene (TPE) as spacer. A blue-shifted emission
appears and strengthens when the pressure is more than 1.23 GPa, and
it reaches the maximum when the pressure is 4.28 GPa. This phenomenon
is ascribed to the cooperative effect between the aggregation-induced
emission of TPE units and energy-transfer suppression from TPE to
an AN excimer. This work reports a new concept in the piezochromic
field and provides a novel strategy to achieve luminescence from a
high-lying excited state.