Synthesis of novel azo dye-based 1,2,4-triazine derivatives and their spectral, fabric and anti-bacterial applications: an integration of solvatochromism, photochromism, colorfastness, TD-DFT and molecular docking analysis

In the current research, a series of five novel azo dyes (1c–5c) were synthesized from azodiene (1a–5a) and azodienophile (1b–5b) via the Diels–Alder reaction. These 1,2,4-triazine derivatives (1c–5c) were synthesized through grindstone synthesis and characterized through ¹³C-NMR and ¹H-NMR. Further, they were evaluated for their dye potential by textile application using an ISO-certified method. The colorfastness properties of these dyes were checked by ISO standard methods on polyester fabric. These were screened for their in vitro antibacterial activities against Gram-negative and Gram-positive bacteria at 50, 100, 150, 200 and 250 mg mL⁻¹ concentrations using cephalosporin as the standard drug. The synthesized dyes/compounds revealed good results against E. coli and Staphylococcus aureus strains. Moreover, molecular docking of these dyes was done by Molegro Virtual Docker with very good MolDock scores. Solvatochromism of these dyes was checked based on their λ_max values, and their photochromism was also checked by applying sunlight to their solvent solutions. These values were compared with experimental and TD-SCF DFT values, showing almost the same results.