Pressure-Induced Emission Enhancement and Piezochromism of Triphenylethylene

Abstract

Pressure-induced emission enhancement (PIEE) is a new phenomenon that has attracted widespread attention in the past few years for improving the solid-state emission efficiency of fluorophores. However, a thorny issue still remains in the study of PIEE. Thus, it is urgent and important to discover and design more PIEE systems for further enhancing the efficiency. In this paper, we found that triphenylethylene (TriPE) showed both conspicuous emission enhancement within the pressure range of 0.0–0.8 GPa and piezochromism behavior upon compression. More interestingly, infrared (IR) analysis indicated that ring-opening reaction of the phenyl ring occurred when pressure was beyond 14.2 GPa. Also, the ring-opening reaction of the phenyl ring led to irreversible optical changes. In situ high-pressure IR spectroscopy and angle-dispersive X-ray diffraction analysis demonstrated that the PIEE of TriPE was attributed to the related C–H···π and C–H···C hydrogen bonds that could inhibit or restrict the movement of aromatic parts remarkably, restraining the energy loss by intramolecular motion. Our study provides insights into the significant effect of intermolecular interactions on fluorescence emission properties.

Facile ACQ-to-AIE transformation via diphenylphosphine (DPP) modification with versatile properties

“…The molecular motions are further inhibited by applying external pressure, contributing to the emission enhancement similar to what has been reported in the literature. [50][51][52][53][54][55][56][57][58][59][60] The rapid intersystem crossing is the internal mechanism of non-luminescence in the solution state, which is different from the previous report that planarization leads to fluorescence quenching. 41…”

Pressure-induced phosphorescence enhancement and piezochromism of a carbazole-based cyclic trinuclear Cu(i) complex

“…[3][4][5][6][7][8][9][10] Recent studies revealed chromic mechanisms of such materials are related to pressure-controllable molecular switch, [11][12][13] phase transition, 14,15 conformational transformation, 16,17 excited state transformation, 18 and aggregation-induced emission (AIE) effect. 19,20 To date, the molecular design and material selection for piezochromism are mostly focused on organic molecules. [21][22][23][24][25] Owing to weak spin-orbital coupling and a long triplet-state lifetime, the pure organic molecules hardly showed strong phosphorescence at room temperature (rt).…”

Understanding the solid state luminescence and piezochromic properties in polymorphs of an anthracene derivative

“…1,25–27 Under elevated pressures a decrease in the emissive response has traditionally been observed and attributed to an increase in π–π stacking interactions that leads to nonradiative decay. 27–33 Whereas an increase in the emissive response has been attributed to mechanisms such as RIR, RIM, the formation of exciton traps and an increase in radiative emission probabilities. 34–39 The emission spectrum is also affected under the application of pressure.…”