Ratiometric Fluorescent Probes Based on Isosteviol with Identification of Maleic Acid in Starchy Foods

Area of Science:

• Analytical Chemistry
• Supramolecular Chemistry
• Chemical Sensing

Background:

• Isosteviol's rigid, saddle-shaped structure offers a unique host-guest recognition cavity.
• Developing selective fluorescent probes for organic acids is crucial for various applications.

Purpose of the Study:

• To construct novel isosteviol-based fluorescent probes (4 and 5) for selective recognition of maleic acid and fumaric acid.
• To evaluate the sensing performance and mechanism of these probes.

Main Methods:

• Synthesis of isosteviol-based fluorescent probes 4 and 5.
• Spectroscopic analysis (fluorescence spectroscopy) to assess probe response.
• Density Functional Theory (DFT) calculations and 1H NMR spectroscopy to elucidate the sensing mechanism.

Main Results:

• Probes 4 and 5 showed high selectivity for maleic acid over fumaric acid, with no significant fluorescence change for fumaric acid.
• Distinct ratiometric fluorescence responses were observed for maleic acid.
• Detection limits for maleic acid were determined as 4.14 × 10⁻⁶ M (probe 4) and 1.88 × 10⁻⁶ M (probe 5).
• Intermolecular hydrogen bonding between probes and maleic acid was confirmed as the sensing mechanism.
• Successful detection of maleic acid in starch-rich food samples (potatoes, sweet potatoes, corn).

Conclusions:

• Isosteviol-based probes 4 and 5 are effective for selective and sensitive detection of maleic acid.
• The probes demonstrate potential for real-world applications, including food analysis.
• This work highlights the utility of isosteviol derivatives in designing advanced fluorescent sensors.