Molecular Association-Induced Emission Shifts for E/Z Isomers and Selective Sensing of Nitroaromatic Explosives

Two 1,2-disubstituted tetraphenylethene E/Z isomers, each containing two cyano functional groups, were successfully synthesized and characterized. Unlike conventional tetraphenylethene molecules, the two isomers possess unique aggregation induced emission red-shift and enhancement behavior. Interestingly, the crystalline solids of these two isomers show distinct emission maxima, which are more than 50 nm apart from each other. These two isomers can selectively detect nitroaromatics, showing a quenching efficiency of picric acid more than 100 times higher than other nitroaromatics. The structural characterization, absorption, and emission in solutions as well as DFT calculations were conducted to help us gain deep insights into the chemistry of these species.