Pressure-Induced Organic Phosphorescence Enhancement: The Key Role of Intramolecular Interactions and Inherent Mechanism

To date, the pressure-dependent luminescence behavior
of purely
organic compounds represents a significant research interest within
the realm of stimulus-responsive smart materials. Most previous studies
have predominantly focused on fluorescence properties, while investigations
into the pressure-regulated room-temperature phosphorescence (RTP)
remain relatively underexplored. This work innovatively proposes a
strategy to achieve pressure-induced RTP enhancement through the introduction
of aromatic carbonyl and intramolecular interactions. The donor–acceptor
structure and ortho-substituted position enables BP-o-DMAC to adopt a twisted V-shaped conformation with intramolecular
C–H···O hydrogen bonds and a charge transfer
feature. Upon compression, the intramolecular C–H···O
interaction is enhanced by pressure, which effectively suppresses
nonradiative energy loss, promotes spin–orbit coupling, and
stabilizes triplet excitons, consequently boosting RTP efficiency
within the pressure range. Comparative experiments further confirm
the crucial role of intramolecular interactions in achieving RTP enhancement.
This work provides a new approach for designing piezochromic materials,
especially with pressure-induced RTP enhancement.