This journal is © The Royal Society of Chemistry and the Chinese Chemical Society 2018 Mater. Chem. Front., 2018, 2, 1595--1608 | 1595 Cite this: Mater. Chem. Front., 2018, 2, 1595 Recent progress in the mechanofluorochromism of distyrylanthracene derivatives with aggregation-induced emission Juan Zhao, Zhihe Chi, Zhiyong Yang,* Zhu Mao, Yi Zhang, * Eethamukkala Ubba and Zhenguo Chi * Mechanofluorochromic (MFC) luminogens, as a group of evidence-based, practical smart materials, have established immense interest with respect to mechanical stimuli, due to their promising applications in various fields like mechanosensors, safety papers, and optical storage. However, MFC luminogens were rare earlier than 2010. After the discovery that MFC is an essential unique feature of aggregation-induced emission (AIE)-active molecules in 2011, researchers are encouraged to pay more attentions toward MCF luminogens, in which field the investigations are hastened steadily and focused distinctly. As one of the most vital AIE cores, distyrylanthracene (DSA) has been extensively used to assemble MFC motifs. As part of the interest in MFC luminogens, this contemporary overview is targeted on recent advances in the mechanofluorochromism of DSA derivatives with AIE properties and mechanistic study, which encourages more researchers to dedicate themselves to this interesting exploration discipline. 1. Introduction Mechanofluorochromic (MFC) luminogens are a class of smart fluorescent molecules which can respond to external forces including mechanical stimuli such as pressing, grinding, crushing, or rubbing with alteration of the emission colors or strengths, and have attracted considerable attention given their promising applications in mechano-sensors, security papers, and optical storage. 1–3 The emission of MFC luminogens can be altered through changes in the molecular structure or aggregate morphology. Although the first one is a general way to tune the emission of a luminogen, limited examples of MFC luminogens have been reported based on this mechanism due to their incomplete and irreversible chemical reactions in the solid state. Even though each system has its own characteristics, the MFC luminescence of most reported luminogens has been achieved during modulation in their morphology by mechanical stimuli. 4 However, prior to this essential discovery that mechanofluoro- chromism is one of the common and unique properties for most aggregation-induced emission (AIE) luminogens, 5 MFC lumino- gens that are dependent on changes in their physical molecular packing modes were very rare. There are two noticeable reasons: 6 firstly, there is a shortage of clear design strategies for their syntheses; secondly, the emission of many luminogens is totally or partially quenched when aggregates are formed due to the aggregation-caused quenching (ACQ) effect. In 2001, Tang et al. 7 suggested a few AIE molecules that emit more efficiently in the aggregated state than in the dissolved form, leading to key examples of anti-ACQ luminogens. Since then, many AIE references such as triphenylethylene, tetraphenyl- ethylene, silole, cyano distyrylbenzene and distyrylanthracene have been used for the development of AIE molecules. 8–13 AIE luminogens have become one of the hottest research topics due to their potential applications in diverse fields, such as organic light-emitting devices (OLEDs) and chemo-sensors. 14 In fact, the development of AIE has surmounted the two aforementioned problems. Recently, a number of AIE luminogens displaying MFC properties have been discovered. For this reason, nowa- days the use of AIE moieties provides an important strategy to construct new compounds and also various mechano-responsive AIE luminogens. During the investigation of AIE, Tang and co-workers found that several AIE luminogens can switch their emission between bright and dark when crystalline and amorphous states are interconverted. 15–17 The first reported investigation regarding the mechano-responsive luminescence of an AIE molecule 18 attempted to prove the AIE mechanism, which was the restriction of intramolecular rotations, by applying hydrostatic pressure to an amorphous film of silole. It was found that the photoluminescence (PL) emission intensity was enhanced by 9% when the pressure PCFM Lab, GD HPPC Lab, Guangdong Engineering Technology Research Center for High-performance Organic and Polymer Photoelectric Functional Films, State Key Laboratory of Optoelectronic Material and Technologies, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, P. R. China. E-mail: chizhg@mail.sysu.edu.cn, ceszy@mail.sysu.edu.cn, yangzhy29@mail.sysu.edu.cn Received 26th March 2018, Accepted 20th May 2018 DOI: 10.1039/c8qm00130h rsc.li/frontiers-materials MATERIALS CHEMISTRY FRONTIERS REVIEW Published on 21 May 2018. Downloaded on 10/3/2021 3:42:59 AM. View Article Online View Journal | View Issue