Cyano and Isocyano-substituted Tetraphenylethylene with AIE Behavior and Mechanoresponsive Behavior

Dual-functional materials with AIE behavior and mechanoresponsive behavior have attracted considerable attention due to their promising applications in mechano-sensors, optical storage, solid-state optoelectric devices and bioimage systems. AIEgens bearing tetraphenylethylene (TPE) core become elementary building blocks in many fluorescent functional materials. In this article, cyanoand isocyano-electronic withdrawing groups are incorporated with TPE skeleton to form tetracyanophenylethylene (TPE-CN) and tetraisocyanophenylethylene (TPE-NC). Their structures are confirmed by NMR, Mass Spectra and single crystal X-ray measurement. These two isomers reflect aggregation-induced emission (AIE) property in solution state and mechanochromic behavior in solid state. Interestingly, their luminescent intensities, quantum yields and fluorescent lifetime in solid state have an obvious increase upon grinding. The theoretical calculation of these two compounds clarify their difference in optical properties. The mechanochromic mechanism is also intensively explained by powder X-ray measurements.

Automated summary

In this article, the dual-functional materials TPE-CN and TPE-NC with aggregation-induced emission (AIE) and mechanochromic behavior were studied. It was found that their luminescent properties in solid state were significantly enhanced upon grinding. The optical properties and mechanochromic mechanism were elucidated through theoretical calculations and experimental verification.