Antagonistic Effects of Distance and Overlap toward Anomalous Pressure-Induced Blueshift of π–π Excimer Fluorescence in 9-(2,2-Diphenylvinyl)anthracene Crystals

作者：Xinqi Yang, Yuxiang Dai, Haichao Liu, Kai Wang, Haile Yan, Xihan Yu, Zhou‐An Xia, Min Wu, Shitong Zhang, Guanjun Xiao, Bo Zou, Bing Yang · 发表于：Journal of the American Chemical Society · 年份：2025 · DOI：10.1021/jacs.4c16582 · 被引用次数：31 · 研究领域：Luminescence and Fluorescent Materials、Organic Light-Emitting Diodes Research、Molecular Sensors and Ion Detection

Piezochromic materials usually exhibit a gradual redshift of emission as pressure increases due to the formation of a low-energy “dark” state, e.g., excimer. However, our study presents an anomalous excimer-based pressure-induced emission blueshift. A crystal was investigated here with a discrete π–π anthracene dimer stacking and excimer emission, and the dimer is characterized by an overshifted off-center stacking pattern. Intriguingly, under isotropic hydrostatic pressure, this crystal exhibits negative linear compressibility almost along the c -axis of the unit cell. Furthermore, an antagonistic effect between overlap ratio (S π–π ) and interplanar distance (D π–π ) within the dimer on emission was identified: reduced D π–π typically dominates the emission redshift, while decreasing S π–π can cause emission blueshift. When the pressure reaches around 5.00 GPa, the π–π excimer fluorescence exhibits an unexpected blueshift, indicating the reign of decreasing S π–π . This study not only sheds light on the modulation of fluorescence properties by noncovalent interactions but also introduces an innovative approach to anomalous piezochromism.