Selective Synthesis of <i>cis</i> and <i>trans</i> o‐Hydroxychalcone Derivatives for Metal Sensing Applications

This study explores a novel synthetic approach for obtaining cis ‐ and trans ‐isomers of o‐hydroxychalcone derivatives and their metal‐sensing capabilities. Four chalcones (CH‐1 to CH‐4) were synthesized using an optimized Claisen–Schmidt condensation reaction. This method efficiently yielded the desired products by combining o‐hydroxyacetophenone with various substituted benzaldehydes in the presence of NaOH. The key innovation lies in the reaction conditions that enable the selective synthesis of both cis- and trans- isomers. Analysis of the allylic protons in CH-1 , CH-2 , and CH-3 using 1 H NMR revealed a coupling constant ( J Hα ‐ J Hβ ) of 15.60 Hz, confirming their trans configuration. Conversely, CH‐4 displayed a coupling constant of J = 8.40 Hz, indicating a cis configuration. Further structure optimization was performed using the B3LYP method with a DFT B3LYP/Lan2DZ level of theory. The metal‐sensing properties and selectivity of the synthesized chalcones were evaluated using UV‐Vis spectroscopy in an ethanolic solution containing various metal ions (Cu 2+ , Fe 3+ , Zn 2+ , K + , Mn 2+ , and Co 2+ ). Interestingly, CH-1 and CH-2 exhibited specific interactions with Cu 2+ ions. In contrast, CH-3 and CH-4 demonstrated the ability to sense both Cu 2+ and Fe 3+ , highlighting their potential for dual metal ion detection. This work presents a novel synthesis method for controlling cis-trans isomerism in o‐hydroxychalcones and unveils their promising uses in selective metal ion–sensing applications.