A Study on the Photoisomerization of (E)-Dehydrozingerone, Its (E)-(E)-C₂ Symmetric Dimer, and Their O-Methylated Derivatives

In this study, UV-induced (<i>E</i>)-to-(<i>Z</i>) geometrical isomerizations of the curcumin degradation product (<i>E</i>)-dehydrozingerone, along with curcumin-inspired (<i>E</i>)-<i>O</i>-methylated dehydrozingerone and their corresponding C₂-symmetric dimers, were investigated. All compounds produced corresponding (<i>Z</i>) isomers in varying yields upon UV irradiation in deuterated solvents. The efficiency of these photoisomerizations depended on the solvent and wavelength used. While (<i>Z</i>) dehydrozingerone and its corresponding (<i>Z</i>)-(<i>Z</i>) dimer proved to be highly unstable during purification, the <i>O</i>-methylated derivatives were successfully isolated, fully characterized by NMR spectroscopy, and further analyzed by UV-Vis spectroscopy and computational methods.