Controlled bio-catalytic synthesis of ampyrone–vanillin macromolecules: Deciphering the transition from nano-oligomers to polymers and the limits of enzymatic stability

This study reports the time-controlled biocatalytic synthesis of nanostructured macromolecules derived from heteroaromatic ampyrone and bio-based vanillin. By optimizing the reaction duration (2, 4, and 6 h) with Horseradish Peroxidase (HRP), stable nano-oligomers (NSO-1, NSO-2) and a robust polymer (nano-pores polymer/NP-P) were successfully isolated. The novelty of this work lies in the precise temporal mapping of the HRP-catalyzed process, identifying a 6 h ‘stability window’ that maximizes molecular growth (Mw = 5743 g/ mol, n ≈ 14) before the onset of enzymatic chain scission. Characterization revealed a significant reduction in the optical band gap from 2.38 eV to 1.49 eV and a morphological transition from macrocrystalline rods to nano porous matrices. These results demonstrate that temporal control in enzymatic synthesis enables fine-tuning of optoelectronic and thermal properties, positioning these sustainable hybrids as viable candidates for organic photovoltaics and smart material technologies.