Respiration‐Responsive Colorful Room‐Temperature Phosphorescent Materials and Assembly‐Induced Phosphorescence Enhancement Strategies

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 19; no. 18; pp. e2207403 - n/a
• Main Authors: Ye, Wenyan, Wang, Yandong, Cao, Tengyang, Meng, He, Wang, Chunlei, Hu, Bingxuan, Gao, Zeyu, Wang, Caiqi
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01-05-2023
• Subjects: Afterglows; Chitosan; color‐tunable phosphorescent systems; Cyclodextrins; Hydrogen bonds; Nanotechnology; Natural polymers; Phosphorescence; Polymer films; room‐temperature phosphorescence; Stimuli; stimulus responsive; supramolecular assembly; supramolecular assembly; color-tunable phosphorescent systems; stimulus responsive; room-temperature phosphorescence
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202207403

It is still very challenging to obtain colorful and long‐afterglow room‐temperature phosphorescent (RTP) materials from pure organic polymers. Herein, it is found that chitosan (CS), a natural polymer, not only has its own RTP, but also reacts with different phosphorescent molecules to obtain a multicolor, long‐afterglow RTP material. CS can emit RTP with a lifetime of 48 ms. In addition, CS is rich in amino groups, and grafting different phosphorescent molecules onto CS by an amidation reaction can modulate it to emit different colors of phosphorescence and obtain a series of colorful CS derivatives. The obtained polymer films also have ultra‐long RTP due to the good film‐forming ability. In addition, one of the CS derivatives selected with α‐cyclodextrin is used to construct RTP materials with lifetimes of up to seconds. The host–guest interactions are used to suppress nonradiative relaxation and build crystalline domains, thus synergistically enhancing the RTP. Interestingly, the RTP properties of the CS derivative films are extremely sensitive to water and heat stimuli, because water broke the hydrogen bonds between adjacent CS molecules and thus altered the rigid environment in the material. Finally, they can be used as a stimuli‐responsive ink and for monitoring environmental humidity.
Intrinsic room‐temperature phosphorescence (RTP) of chitosan (CS) and colorful RTP studies of CS derivatives is reported. One of the CS derivatives selected with α‐cyclodextrin (α‐CD) is used to construct room‐temperature phosphorescent materials with a threefold increase in lifetime. Due to the rich water/heat sensitivity of the CS derivative materials, they can be used for monitoring human respiration and environmental humidity.