Comparative Study of Enzymatic and Oxidative Polymerization of a Benzothiazole-Based Schiff Base and Its Antibacterial Properties

In this study, the Schiff base 1-(((6-nitrobenzo[d]thiazol-2-yl) imino)methyl)naphthalen-2-ol (NBTIMN) was synthesized and subsequently polymerized by two different methods. Oxidative polymerization in the presence of organic (o-(NBTIMN)-O) and aqueous alkaline media (o-(NBTIMN)-A) was one of the techniques. The other was enzyme-catalyzed oxidative polymerization (o-(NBTIMN)-E), which was conducted at room temperature with hydrogen peroxide and the enzyme horse radish peroxidase (HRP). The structures of the obtained oligomers were characterized using FT-IR, 1H-13C-NMR, UV–Vis, CV, and GPC analyses, and their electrochemical and optical band gaps were determined as 2.68, 2.66, and 2.49 eV, and 3.08, 2.90, and 3.07 eV for o-(NBTIMN)-O, o-(NBTIMN)-A, and o-(NBTIMN)-E, respectively. Thermal analyses demonstrated that the o-(NBTIMN)-O and o-(NBTIMN)-A derivatives exhibited enhanced thermal stability, characterized by higher decomposition temperatures and LOI values. SEM analyses revealed distinct differences in surface morphologies depending on the polymerization conditions. Antibacterial assays showed that o-(NBTIMN)-O exhibited the strongest broad-spectrum inhibition, whereas NBTIMN displayed pronounced activity against S. aureus. In contrast, o-(NBTIMN)-A and o-(NBTIMN)-E were found to be inactive. These results highlight the critical influence of polymerization conditions on both the physicochemical characteristics and the biological activities of the synthesized structures. Importantly, the comparative design of enzymatic and chemical polymerization demonstrates the potential for environmentally friendly synthesis strategies. The distinct electrochemical and thermal properties suggest applicability in electronics and sensor-related fields, while the pronounced antibacterial activity of o-(NBTIMN)-O holds promise for biomedical and antimicrobial applications.