Synthesis, Characterization, and Dual Functional Properties of Coumarin-Based Hybrids for Biological and Optical Applications

Heterocyclic compounds incorporating nuclei of coumarin,
benzimidazole,
and benzothiazole exhibit significant biological and pharmacological
properties. This study presents an efficient synthetic route for hybrid
molecules integrating coumarin with either benzimidazole or benzothiazole
under mild reaction conditions. The antibacterial and antioxidant
properties of the synthesized compounds were systematically evaluated.
The methodology successfully yielded 11 compounds in total, including
six substituted coumarin–benzimidazole and five coumarin–benzothiazole
derivatives, with yields ranging from 14 to 60%. Notably, derivatives 19 and 26 exhibited moderate antibacterial activity against Staphylococcus aureus at concentrations of 500 and
250 μg·mL–1, respectively. Derivatives 26 and 33 demonstrated strong antioxidant activity, with DPPH radical scavenging
rates between 89 and 72%. Structure–activity relationship analysis
revealed that substituents at position 7 of the coumarin nucleus significantly
enhance antioxidant activity. Density functional theory calculations
were performed to evaluate the compounds. Multivariate statistical
methods, such as principal component analysis, identified molecular
volume and bond order as key determinants of biological activity.
Additionally, optical properties were explored, revealing promising
photoluminescence characteristics with emission ranging from 446 to
502 nm. These findings suggest potential applications in theranostics
and optoelectronics. This work highlights the importance of structural
modifications in optimizing the biological and optical properties
of coumarin-based hybrids, providing a foundation for future studies
aimed at expanding their biomedical and technological applications.