Dynamic Phosphorescence and Real‐Time Temperature Visualization via Synergy of Acetalization and Hydrogen Bonding

ABSTRACT Organic phosphorescent materials exhibited potential in intelligent sensing. However, achieving phosphorescent materials that respond to temperature with phosphor peak shift is still challenging. Herein, based on synergy between reversible acetalization and hydrogen bonding, vanillin‐doped cellulose films (vanillin/HEC) are developed, which exhibited 14.0 nm redshift of a temperature‐dependent spectrum from 77 to 180 K. Characterization results revealed that hydrogen bonding effectively inhibited the non‐radiative decay and induced a decline in the T 1 energy level of vanillin. As the temperature rose, the increased degree of acetalization of vanillin with HEC resulted in a phosphorescence spectra redshift from 476 to 490 nm. In the study of factors influencing dynamic performance, molecular engineering revealed that electron‐rich substituents on vanillin increased the aldehyde group's electron density, inhibiting acetalization and diminishing dynamic response. Furthermore, adjusting the branch lengths or substituent types of matrices changed the binding energy with vanillin, resulting in a redshift varied from 4.6 to 19.6 nm. Moreover, modifying HEC with PVA enhanced the rigidity of vanillin/HEC, expanding the temperature response range from extremely low (77 K) to high (334 K). Notably, vanillin/HEC has successfully achieved visualization of temperature distribution. This work provides an effective approach for advanced large‐area non‐contact visualization.