1,2,4-Triazole-Based Excited-State Intramolecular Proton Transfer-Driven "Turn-On" Chemosensor for Selective Cyanide...

Area of Science:

• Analytical Chemistry
• Materials Science
• Environmental Science

Background:

• Cyanide (CN-) is a highly toxic anion with significant environmental and biological implications.
• Sensitive and selective detection platforms for cyanide are crucial.
• Existing methods may lack the required sensitivity or selectivity for certain applications.

Purpose of the Study:

• To design and synthesize a novel excited-state intramolecular proton transfer (ESIPT)-based chemosensor for cyanide detection.
• To investigate the sensing mechanism and performance of the developed chemosensor.
• To explore the practical applications of the chemosensor in environmental monitoring and security.

Main Methods:

• Synthesis of a novel ESIPT-based chemosensor (TSB) from 2-hydroxy-1-naphthaldehyde and 4-amino-1,2,4-triazole.
• Computational studies including TD-DFT, reduced density gradient scatter plots, and simulated infrared spectra.
• Spectroscopic analysis (UV-Vis, fluorescence), 1H NMR, and FT-IR to characterize the chemosensor and its interaction with cyanide.
• Determination of binding constant and stoichiometry.

Main Results:

• The chemosensor exhibited a naked-eye color change from colorless to yellow and a "turn-on" fluorescence response (color to teal) upon addition of CN-.
• High selectivity for CN- over other common anions was observed, with a low detection limit of 0.41 μM.
• Mechanistic studies confirmed a deprotonation-driven interaction and enhanced hydrogen bonding in the excited state, with a binding constant of 1.98 × 10^5 M^-1 and 1:1 stoichiometry.
• The chemosensor demonstrated utility in test strip development and as a component in a molecular keypad lock.

Conclusions:

• A novel ESIPT-based chemosensor (TSB) was successfully developed for sensitive and selective cyanide detection.
• The chemosensor provides a visual and fluorescent response, enabling real-time monitoring.
• The developed platform shows promise for practical applications in environmental analysis, safety, and security systems.