Gu Yarong, Wang Kai, Dai Yuxiang, Xiao Guanjun, Ma Yuguo, Qiao Yuancun, Zou Bo
State Key Laboratory of Superhard Materials, Jilin University , Changchun 130012, China.
Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering and the Key Lab of Polymer Chemistry & Physics of the Ministry of Education, College of Chemistry, Peking University , Beijing 100871, China.
J Phys Chem Lett. 2017 Sep 7;8(17):4191-4196. doi: 10.1021/acs.jpclett.7b01796. Epub 2017 Aug 22.
Pressure-induced emission enhancement (PIEE), a novel phenomenon in the enhancement of the solid-state emission efficiency of fluorophores, has been arousing wide attention in recent years. However, research on PIEE is still in the early stage. To further pursue more enhanced efficiency, discovering and designing more PIEE systems would be urgently desirable and of great importance. In this Letter, we found that carbazole presented a conspicuous emission enhancement under high pressure up to 1.0 GPa. In situ high-pressure infrared spectroscopy and angle-dispersive X-ray diffraction analysis combined with Hirshfeld surface theory calculation indicated that the PIEE of carbazole was attributed to the decrease of the nonradiation vibration process. This phenomenon mainly resulted from restriction of the N-H stretching vibration by increased N-H···π interactions under high pressure. Our study puts forward a mechanism of PIEE related to the restriction of intramolecular vibration, which provided deep insight into the essential role of intermolecular interaction in fluorescence emission properties.
压力诱导发光增强（PIEE）是一种增强荧光团固态发光效率的新现象，近年来引起了广泛关注。然而，对PIEE的研究仍处于早期阶段。为了进一步追求更高的效率，发现和设计更多的PIEE体系将是迫切需要且至关重要的。在本信函中，我们发现咔唑在高达1.0 GPa的高压下呈现出显著的发光增强。原位高压红外光谱和角散射X射线衍射分析结合 Hirshfeld 表面理论计算表明，咔唑的PIEE归因于非辐射振动过程的减少。这种现象主要是由于高压下 N-H···π相互作用增加对N-H伸缩振动的限制所致。我们的研究提出了一种与分子内振动限制相关的PIEE机制，这为深入了解分子间相互作用在荧光发射性质中的重要作用提供了依据。
