Two tetraphenylethene-pyrene isomers: Distinct fluorescence and mechanochromic properties. (February 2021)

• Record Type: Journal Article
• Authors: Zhang, Hongyan; Zhang, Han; Huang, Guangxi; Li, Bing Shi
• Is Part Of: Dyes and pigments. Volume 185(2021)Part B
• Publication Date: 2021-02
• Subjects: Mechanochromism -- Aggregation induced emission -- Tetraphenylethene -- Pyrene; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2020.108947
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: 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, λem = 456 nm, Φfl = 5.5%; green, λem = 504 nm, Φfl = 3.3%; dim, λem = 461 nm, Φfl = 0.9%) may be promising in the application of optical recording. Graphical abstract: Image 1 Highlights: ∙ Two isomers 1 and 2 were obtained through the combination of tetraphenylethene and pyrene unit with subtle difference in their connection. The subtle difference in the connection of ester group led to their diverse photophysical and mechanochromic properties. ∙ 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 remained ACQ property. ∙ The three-state mechanochromic fluorescence of 1 made it a promising optical recording material.