Photocatalytic Synthesis of Coumarin Derivatives Using Visible-Light-Responsive Strawberry Dye-Sensitized Titanium Dioxide Nanoparticles

This study presents a novel method for the photocatalytic synthesis of 4-aryl-6-(3-coumarinyl) pyrimidin-2 (1H)-ones (a coumarin derivative) using strawberry dye-sensitized TiO₂ (SD-TiO₂) under visible light. The synthesis of 4-aryl-6-(3-coumarinyl) pyrimidin-2 (1H)-ones was achieved through a three-component, one-pot condensation reaction involving 3-acetyl coumarin, aldehydes, and urea, utilizing SD-TiO₂ as a reusable and innovative photocatalyst at room temperature. The resulting SD-TiO₂ photocatalyst was thoroughly characterized using FT-IR, XPS, XRD, SEM, and BET. The efficacy of SD-TiO₂ was evaluated by comparing it to pristine TiO₂ in terms of photocatalytic activity, and the optimal conditions for the synthesis process were determined. Notably, the SD-TiO₂ photocatalyst exhibited a maximum yield of the compound, reaching up to 96% in just 30 min with a catalyst concentration of 1 mg/mL. This yield surpasses traditional thermal procedures employing reflux conditions, where 1 mg/mL of SD-TiO₂ is sufficient to complete the reaction. The resulting 4-aryl-6-(3-coumarinyl) pyrimidin-2 (1H)-ones were further characterized using ¹H-NMR and ¹³C-NMR. Moreover, the stability of the SD-TiO₂ photocatalyst was confirmed through recyclability experiments and spectroscopic characterization, demonstrating its practicality for up to three consecutive reaction cycles.