Clustering-triggered Emission of Nonaromatic Polymers with Multitype Heteroatoms and Effective Hydrogen Bonding

Nonconventional luminophores without large conjugated structures are attracting increasing attention for their unique aggregation-induced emission(AIE) properties and promising applications in optoelectronic and biomedical areas. The emission mechanism, however, remains elusive, which makes rational molecular design difficult. Recently, we proposed the clustering-triggered emission(CTE) mechanism to illustrate the emission. The clustering of electron-rich nonconventional chromophores with pi and/or n electrons and consequent electron cloud overlap is crucial to the luminescence. Herein, based on the CTE mechanism, nonaromatic polymers containing multitype heteroatoms(i.e., O, N, and S) and involving amide(CONH) and sulfide(-S-) groups were designed and synthesized through facile thiol-ene click chemistry. The resulting polymers demonstrated typical concentration-enhanced emission, AIE phenomenon, and excitation-dependent emission. Notably, compared with polysulfides, these polymers exhibited much higher solid-state emission efficiencies, because of the incorporation of amide units, which contributed to the formation of emissive clusters with highly rigidified conformations through effective hydrogen bonding. Furthermore, distinct persistent cryogenic phosphorescence or even room temperature phosphorescence(RTP) was noticed. These photophysical behaviors can well be rationalized in terms of the CTE mechanism, indicating the feasibility of rational molecular design and luminescence regulation.

Automated summary

This study proposes a novel design method for nonaromatic luminescent polymers based on the clustering-triggered emission mechanism, showing typical concentration-enhanced emission, AIE phenomenon, excitation-dependent emission, as well as higher solid-state emission efficiencies and phosphorescent characteristics compared with polysulfides.