Aggregation-induced emission (AIE) molecules are important research objects in the fields of chemical sensing, bioimaging, and optoelectronics. Among them, the luminescence properties of polysubstituted olefin AIE molecules can be precisely adjusted by regulating the molecular structure, making them an important member of the AIE molecule family. At present, traditional methods for synthesizing polysubstituted olefins often use McMurry or Horner-Wadsworth-Emmons reactions, which have low reaction activity, poor chemical selectivity, and harsh reaction conditions, which greatly restrict the development of such materials. Therefore, it is urgent to develop efficient, environmentally friendly, and mild synthesis methods to promote the further development of AIE molecules.

Figure 1. Comparison between the traditional method and the C−S activation method

In this paper, a new cross-coupling reaction based on carbon-sulfur (C−S) bond activation was developed. This method uses inexpensive raw materials dimethylarylsulfinic acid trifluoromethanesulfonate and p-toluenesulfonylhydrazone as substrates to successfully synthesize more than 40 multi-substituted olefins. Studies have shown that the emission spectrum range of AIE molecules (covering 350-850 nm) can be regulated by adjusting the substrate substituents. Through in-depth deuterium labeling and other work, it was confirmed that β−H elimination plays a key role in the formation of double bonds. In addition, through a series of control experiments, the importance of lithium tert-butoxide in activating Buchwald precatalysts and promoting the generation of highly active diazo intermediates was verified. Finally, this paper used AIE molecules with a fluorescence quantum yield of up to 65.8% to prepare nanoparticles. The results show that these nanoparticles have good localization ability in cells and exhibit excellent biocompatibility, showing potential application prospects in the biomedical field.

Figure 2. AIE molecules synthesized by C−S activation method, with emission spectra covering 350 to 850 nm, including chemical structure, yield, and fluorescence spectra

Therefore, this study developed a low-cost and efficient synthesis method for synthesizing AIE molecules through C−S bond activation. This method not only greatly improves the synthesis efficiency of multi-substituted olefins, but also achieves precise regulation of the optical properties of AIE molecules, showing broad application potential in chemical sensing, bioimaging and other fields.

The above research paper was published in the journal Aggregate under the title "General method to synthesize aggregation-induced emission molecules via carbon-sulfur bond activation". The first author of the paper is Ma Bowei, a doctoral student in the research group, and the corresponding authors are Professor Huang Hui, Professor Shi Qinqin and Dr. Wen Kaikai of the Beijing Institute of Nanoenergy and Systems of the Chinese Academy of Sciences.