Three tridentate imine ligands containing N2S donors were synthesized via Schiff condensation between derivatives of both amino triazine and 2-carbonyl pyridine. The reaction of these ligands with CuCI2 in a molar ratio of 1:1 provides three Cu(II) complexes with the general formula [CuLn·Cl2]. Analytical, electrical, magnetic, and spectroscopic studies were used to assign the molecular formulae of these metallic chelates. Density function theory (DFT) calculations confirmed the structural analysis results obtained from spectroscopic studies. The various characterization techniques used demonstrated the pentacoordinated slightly distorted square pyramidal structure for the present Cu(II) complexes 1, 2, and 3. Measurements of cyclic voltammetry were done in methanol to define the electrochemical behavior of the current Cu(II) complexes. The biomimetics of catechol oxidase (C.O.) and phenoxazinone synthase (PHS) have been studied in the aerobic oxidation of some phenolic substrates, such as 3,5-di-tert-butylcatechol (3,5-DTBCH2) and ortho-aminophenol (o-APH3). The three candidate oxidase mimetics showed promising activity in the order 3>1>2. The catalytic activity related to the structural properties of existing oxidase mimetics was discussed. The driving force (−ΔG°) controlling the redox reactions of the present biomolecules was calculated from the redox data of Cu(II) complexes 1, 2, and 3. The potential catalytic reaction pathway for the oxidation of the studied phenolic substrates was discussed.