<p>The current study is investigated the synthesis, structural characterization, and antimicrobial evaluation of a terpolymer and its polychelate. The terpolymer (SPF) was synthesized from <i>p</i>-Semidine (<b>1</b>) and <i>p</i>-Phenylenediamine (<b>2</b>) with Formaldehyde (<b>3</b>) through a polycondensation method using dimethylformamide as a reaction medium. Terpolymer-poly chelate with copper was prepared from SPF ligand using a molar ratio of 1: 2 (Cu²⁺: ligand). The structures of the synthesized ligand and its polychelate were characterized using elemental analysis, Fourier Transform Infrared, UV–visible, and Nuclear Magnetic Resonance (¹H &amp; ¹³C) spectral studies. The average molecular weights of the SPF terpolymeric ligand was determined by gel permeation chromatography. The <i>in-vitro</i> experimental studies of SPF Terpolymeric ligand and its copper complex as antimicrobial agents were tested against <i>Candida albicans, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus</i> using the disc diffusion method, with Gentamicin serving as the reference for comparison. The antimicrobial studies revealed that the synthesized compounds exhibited promising results, comparable to a standard drug. Notably, the SPF metal complex demonstrated superior activity against Bacillus Subtilis (30&#xa0;mm/ml) and <i>Pseudomonas aeruginosa</i> (26&#xa0;mm/ml) compared to the ligand. The zone of inhibition is a key indicator in antimicrobial testing, reflecting the effectiveness of antimicrobial agents at various concentrations and offering valuable insights into their potential applications in preventing or treating microbial infections. The <i>in-vitro</i> experimental studies have been validated with the DFT, Molecular docking, and ADMET studies and found that the synthesized terpolymer and its polychelate were potent antibacterial and antifungal agents. In addition, the anti-destructive effect of SPF terpolymer resin on mild steel in sulphuric acid was assessed by mass-loss and electrochemical performances. By forecasting the mechanism of adsorption, thermodynamic and kinetic statistics were intended. Based on the collected data, the inhibition efficiency (%) is computed, demonstrating the terpolymer resin’s ability as a corrosion inhibitor, with an optimal concentration of 1 × 10⁻³&#xa0;M exhibiting an inhibitory efficacy of 92.90%. Absorption and DFT modules are also used to study the molecular level coating of SPF polymer on the mild steel exterior. The result of conceptual module runs illustrated SPF polymer developed π-orbitalis interaction on head and tail fragments with the mild metal, which leads the better corrosion inhibition. The predictable information exposed SPF resin that exhibited good anticorrosive consequences on mild steel in destructive media.</p> Graphical Abstract <p></p>