AIE Stereoisomers with Huge Differences in Luminescence Behavior and Biomedical Activity

Abstract

Stereoisomers that differ only in spatial orientation of their atoms could exhibit distinctive properties and have attracted immense interest in drug development and material science. Herein, a series of AIE-featured stereoisomers with pronounced difference in luminescent and biomedical activities were efficiently synthesized and easily purified. One of the isomers in the E/Z pair is emissive with high fluorescence quantum yield at room temperature, while the other one is nearly non-emissive. As the isomers could transform between each other under UV irradiation, the light-up cell imaging was successfully demonstrated using the non-emissive isomer as a turn-on probe via isomerization process. Analysis of crystal packing patterns illustrated that the contrasts in void space possibly caused the difference in molecular motion and thus led to their distinct luminescence properties. Further, the E/Z isomers displayed remarkable difference in enzymatic conversion rates and cellular toxicities for several cancer cell lines. The distinctive luminescence properties of the isomeric pair provided a powerful tool to image those divergencies in biomedical activity, holding great potential for visualizable drug screening and development.

Tetraphenylethene‐Based cis/trans Isomers for Targeted Fluorescence Sensing and Biomedical Applications

“…Tang and coworkers designed a series of AIE-active cis/trans isomers, in which the TPE framework was modified by substituting one phenyl ring with a cyano group. [33] The isomers with additional modifications of methoxy or hydroxyl groups were found to have limited cellular uptake. In contrast, the introduction of a phosphate group yielded a pair of isomers with enzymatic responsiveness to alkaline phosphatase (ALP) and cell permeability.…”

Photo‐Responsive Fluorescent Materials with Aggregation‐Induced Emission Characteristics

“…The E/Z isomers not only displayed significant disparities in fluorescence properties, but also could controllably transform between E isomer and Z isomer via photo-isomerization under UV irradiation. [101] In addition, by tracing the photo-isomerization process, Tang and coworkers demonstrated that E/Z isomerization was only an insignificant factor, whereas intramolecular rotation was the major reason for the fluorescence quenching of TPE derivatives in solutions. [102] Tang et al reported an approach for "seeing" and controlling the photo-isomerization of the AIE-active 2-ureido-4[1H]-pyrimidinone functionalized TPE isomers.…”