Organic luminescent materials have many potential applications. Developing multifunctional luminescent materials can be helpful for expanding these uses. The unique structural characteristics of tetraphenylethene (TPE) and naphthalimide, for example, endow them with different functions. However, combining these two units to design multifunctional molecules is still challenging.

Jun Yin, Central China Normal University, Wuhan, Wenbo Zhao, Nanjing Normal University, China, and colleagues have designed and synthesized a TPE derivative substituted with a sulfonyl-based naphthalimide unit. The various functions of the resulting molecule (TPE-Np, pictured) were realized by simply changing its physical states: it can be used in solution, in the form of aggregates, as a solid, or attached to a nanogel.

A solution of TPE-Np in a mixture of dimethylsulfoxide (DMSO) and phosphate‐buffered saline (PBS) can efficiently distinguish glutathione (GSH) from cysteine and homocysteine in the presence of cetyltrimethylammonium bromide (CTAB). Using a poly(ethylene glycol)–polyethylenimine (PEG‐PEI) nanogel as a carrier to crosslink TPE-Np allowed the team to obtain a water-soluble nanoprobe with greatly improved biocompatibility. This nanoprobe was successfully used for the visualization of GSH level in living cells.

TPE-Np has aggregation-induced emission (AIE) behavior. It also shows an unexpected highly reversible mechanochromism in the solid state, which was attributed to a change between crystalline and amorphous states. This work could be helpful for the design of other multifunctional fluorescent materials.

• A Versatile Naphthalimide-Sulfonamide-Coated Tetraphenylethene: Aggregation-Induced Emission Behavior, Mechanochromism, and Tracking Glutathione in Living Cells,
  Xie Han, Yuhong Liu, Guotao Liu, Jing Luo, Sheng Hua Liu, Wenbo Zhao, Jun Yin,
  Chem. Asian J. 2019.
  https://doi.org/10.1002/asia.201801854