Two tetraphenylethene-pyrene isomers: Distinct fluorescence and mechanochromic properties

作者：Zhang, Hongyan; Zhang, Han; Huang, Guangxi^*; Li, Bing Shi^*

来源：Dyes and Pigments, 2021, 185: 108947.

DOI：10.1016/j.dyepig.2020.108947

• Mechanochromism
• Aggregation induced emission
• Tetraphenylethene
• Pyrene

Melding aggregation induced emission (AIE) scaffolds with aggregation caused emission quenching (ACQ) luminophores might eliminate the ACQ effect and endow such derived molecules with AIE properties and other novel optical behavior. How the AIE scaffold connects with the ACQ luminophore is critical to determine the properties of the resultant molecules. Melding the tetraphenylethene (TPE) building block with pyrene, isomers 1 and 2 were obtained with an ester group connected in different orientations. Molecule 1 with pyrene connecting with the carbonyl of the ester group possessed aggregation induced emission enhancement (AIEE) and three-state mechanochromic behavior, while molecule 2 with pyrene connecting with the oxygen atom of the ester group still exhibited ACQ property. Theoretical calculations revealed that the connection manner with ester group impacted the charge distribution and molecular conformation of these two isomers, thus resulting in their different fluorescence properties in solution and aggregate states. Mechanochromic molecule 1 with three fluorescence states (blue, lambda(em) = 456 nm, Phi(fl) = 5.5%; green, lambda(em) = 504 nm, Phi(fl) = 3.3%; dim, lambda(em) = 461 nm, Phi(fl) = 0.9%) may be promising in the application of optical recording.