A New Schiff Base Based Fluorescent Sensor for Al(III) Based on 2-Hydroxyacetophenone and o-Phenylenediamine

Area of Science:

• Analytical Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Schiff bases are versatile ligands with applications in coordination chemistry and sensing.
• Developing selective and sensitive fluorescent sensors for metal ions is crucial for environmental and biological monitoring.
• Aluminum ions (Al³⁺) play significant roles in biological systems and industrial processes, necessitating accurate detection methods.

Purpose of the Study:

• To synthesize and characterize a Schiff base (L) derived from 2-hydroxyacetophenone and o-phenylenediamine.
• To investigate the potential of Schiff base (L) as a fluorescent sensor for Al³⁺.
• To evaluate the selectivity and sensitivity of the sensor towards Al³⁺ in the presence of other metal ions.

Main Methods:

• Synthesis of Schiff base (L) via condensation reaction.
• Fluorescence spectroscopy for sensing studies.
• Cyclic voltammetry and square wave voltammetry for electrochemical analysis.
• Density Functional Theory (DFT) calculations for mechanistic insights.

Main Results:

• The Schiff base (L) exhibited a significant fluorescence enhancement (ca. 9.0 fold) upon binding with Al³⁺.
• The sensor demonstrated high selectivity for Al³⁺ over a range of other metal ions, including Zn²⁺, Hg²⁺, Cd²⁺, Pb²⁺, and Fe³⁺.
• A low detection limit of 10^-4.3 M for Al³⁺ was achieved.
• Electrochemical studies showed distinct changes upon Al³⁺ interaction, and DFT calculations supported a 1:1 binding stoichiometry.
• The sensing mechanism was found to be reversible with respect to Na₂EDTA.

Conclusions:

• The synthesized Schiff base (L) is an effective and highly selective fluorescent sensor for Al³⁺.
• The sensor offers a sensitive and reversible method for Al³⁺ detection, applicable in various analytical contexts.
• The combination of spectroscopic and electrochemical techniques, along with theoretical calculations, provides a comprehensive understanding of the sensing mechanism.