Synthesis of 3-(4-Hydroxy-3-Methoxyphenyl)-1-(2-Hydroxyphenyl)-Propenone as a Colorimetric Chemosensor for Hydrogen Phosphate Anions

Hydrogen phosphate is an important anion in environmental and biological systems; however, its excessive presence in water can contribute to eutrophication and water quality degradation. The synthesis and application of 3-(4-hydroxy-3-methoxyphenyl)-1-(2-hydroxyphenyl)-propenone (HMPP) as a colorimetric chemosensor for hydrogen phosphate (HPO₄²⁻) anions have been investigated. HMPP was synthesized via Claisen–Schmidt condensation of vanillin and 2-hydroxyacetophenone, obtained in 34% yield of the target compound. The colorimetric response of HMPP was evaluated toward various anions, including F⁻, Cl⁻, Br⁻, CN⁻, HPO₄²⁻, and CO₃²⁻. The results showed that HMPP exhibited a distinct response toward HPO₄²⁻; however, the presence of other anions caused varying degrees of interference, with CO₃²⁻ showing minimal effect, while Cl⁻, CN⁻, and Br⁻ reduced the response to a greater extent. This behavior is attributed to hydrogen-bonding interactions between HMPP and HPO₄²⁻, which enhance intramolecular charge transfer (ICT). The applicability of HMPP was further evaluated in spiked tap water samples, demonstrating satisfactory recovery in the range of 105.47–107.50%, indicating acceptable accuracy and reliability. Therefore, HMPP demonstrates potential as a colorimetric chemosensor for hydrogen phosphate anions in water samples.