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Temperature-dependent ratiometric fluorescence from an organic aggregates system.
Jie Huang1, Aidong Peng, Hongbing Fu
1Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, P. R. China.
The Journal of Physical Chemistry. A
|July 21, 2006
Summary
Aggregates of 2-(2'-hydroxyphenyl)benzoxazole (HBO) exhibit distinct green and blue emissions due to excited-state intramolecular proton transfer (ESIPT). This property enables their use as robust molecular fluorescent temperature sensors.
Area of Science:
- Photophysics
- Supramolecular Chemistry
- Materials Science
Background:
- 2-(2 ahydroxyphenyl)benzoxazole (HBO) is a molecule known for excited-state intramolecular proton transfer (ESIPT).
- Understanding the photophysical properties of HBO aggregates in aqueous systems is crucial for developing novel sensing applications.
Purpose of the Study:
- To prepare and investigate the photophysical properties of 2-(2 ahydroxyphenyl)benzoxazole (HBO) aggregates in aqueous dispersion.
- To explore the temperature-dependent fluorescence behavior of HBO aggregates and solvated enols.
- To evaluate the potential of HBO aggregates as molecular fluorescent temperature sensors.
Main Methods:
- Preparation of 2-(2 ahydroxyphenyl)benzoxazole (HBO) aggregates.
- Investigation of photophysical properties in aqueous dispersion.
- Exploration of temperature effects on fluorescence emission.
Main Results:
- Coexistence of HBO aggregates and solvated enols in aqueous dispersion.
- Aggregates exhibit green emission via ESIPT (keto form), while solvated enols show blue emission.
- Fluorescent ratiometric change observed between 15 and 60°C, indicating temperature sensitivity.
Conclusions:
- A temperature-dependent equilibrium mechanism between aggregates and solvated enols explains the observed fluorescence changes.
- The reversibility, robustness, and stability of HBO aggregates are suitable for practical applications.
- HBO aggregates show promise for development into molecular fluorescent temperature sensors and thermometers.