Chelation-enhanced fluorescence-enabled coumarin-hydrazone Schiff bases for the detection of Al3+ ions and its real-time applications

• Published in: Journal of molecular structure 2024-04, Vol.1302, p.137411, Article 137411
• Main Authors: Ramasamy, Selva Kumar, Chinnathambi, Arunachalam, Ali Alharbi, Sulaiman, Venkatesan, Geetha, Pugazhendhi, Arivalagan, Sathiyan, Govindasamy
• Format: Article
• Language: English
• Subjects: Aluminum; Chelation-enhanced fluorescence; Chemosensors; DFT Study; Fluorescence; Test Strip
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2023.137411

•A novel Schiff base probe (L) based on coumarin carbohydrazide was synthesized and characterized using various spectroscopic techniques.•The probe L could detect Al3+ via CHEF fluorescence in an aqueous DMSO solution.•The binding interaction of probe L with Al3+ was investigated using FTIR, 1H NMR, ESI mass, and DFT calculations.•The paper strip and probe L were used to detect Al3+ in real-time in diverse water samples. We designed a simple coumarin-hydrazone-based Schiff base fluorescent probe, namely 7-(diethylamino)-N'-(2,4-dihydroxybenzylidene)-2-oxo-2H-chromene-3-carbohydrazide (L), which was successfully synthesized and utilized for selective detection of Al3+ ion via fluorescence ‘turn-on’ method. The Probe L could detect Al3+ by a sharp increment in fluorescence intensity (∼15 times) in a semi-aqueous DMSO medium. The detection limit of L towards Al3+ was calculated to be 50 nM, and the former undergoes a 1:1 stoichiometry binding with a higher binding constant of ∼ 2.14 × 104 M−1. Probe L detects Al3+ by the well-known chelation-enhanced fluorescence (CHEF) mechanism and inhibits C = N isomerization by fluorescence time-resolved measurement. Experimental results from FT-IR, NMR, and ESI mass spectrometry confirm the interaction mechanism between probe L and Al3+ ions, further supported by DFT calculations. In addition, the probe L fabricated paper strips could detect Al3+ in the naked eye under UV light. [Display omitted]