A Highly Sensitive ESIPT-Based Ratiometric Fluorescence Sensor for Selective Detection of Al(3.)
Sanghamitra Sinha, Bijit Chowdhury, Pradyut Ghosh1
1Department of Inorganic Chemistry, Indian Association for the Cultivation of Science , 2A & 2B Raja S. C. Mullick Road, Kolkata 700 032, India.
Inorganic Chemistry
|August 30, 2016
Summary
A new sensor detects aluminum ions (Al(3+)) with high sensitivity and selectivity using excited-state intramolecular proton transfer (ESIPT). This fluorescent probe works in acetonitrile and aqueous systems, enabling precise aluminum detection at low concentrations.
Area of Science:
- Analytical Chemistry
- Materials Science
- Spectroscopy
Background:
- Aluminum (Al(3+)) is crucial in biological systems but toxic at high levels.
- Developing selective and sensitive fluorescent sensors for Al(3+) is essential for environmental and biological monitoring.
- Excited-state intramolecular proton transfer (ESIPT) offers a mechanism for ratiometric fluorescence sensing.
Purpose of the Study:
- To develop a highly sensitive and selective ratiometric fluorescence sensor for Al(3+) detection.
- To investigate the sensor's performance in both organic (acetonitrile) and aqueous solvent systems.
- To elucidate the sensing mechanism using spectroscopic and computational methods.
Main Methods:
- Synthesis and characterization of the ESIPT-based sensor molecule (1H).
- Photophysical studies including UV-visible absorption, steady-state, and time-resolved fluorescence spectroscopy.
- Density Functional Theory (DFT) calculations to model the aluminum complex and confirm the ESIPT mechanism.
Main Results:
- The sensor (1H) exhibits a ratiometric fluorescence response to Al(3+) in acetonitrile, with a color change from cyan to deep blue and a ~2.3-fold emission enhancement.
- In a 90% aqueous system, the sensor shows enhanced selectivity for Al(3+), with a color shift from pale green to deep blue and a ~6-fold emission enhancement.
- The detection limit for Al(3+) is as low as 0.5 nM, demonstrating high sensitivity.
- DFT calculations and comparison with an analogue confirm the ESIPT mechanism and the formation of the aluminum complex.
Conclusions:
- The developed ESIPT-based sensor (1H) is a highly sensitive and selective probe for Al(3+) detection.
- The sensor demonstrates robust performance in both organic and aqueous environments, making it versatile for various applications.
- The study provides a mechanistic understanding of the Al(3+) sensing process via ESIPT.
