Synthesis, characterization and antioxidant screening of a 1,10-phenanthroline-based tetraza-macrocyclic ligand and its nickel complex with therapeutic potential and catalytic significance

In this study, we present a synthetic route for the preparation of a novel 1,10- phenanthroline-based tetraza-macrocyclic ligand, 5,12,25,28-tetraazaheptacyclo [14.8.4.2⁴,⁷.210,13.0⁶,11.019,27.022,26]dotriaconta-1 (25),4,6,8,10,12,16(28),17,19(27),20,22(26),23,29, 31-tetradecaene, 3 and its corresponding nickel complex, (28Z)-1,3,6,31-tetraaza-2-nickelaoctacyclo [17.9.3.2⁷,28.0³,16.0⁴,13.0⁵, 10.022,30.025,29]tritriaconta-4(13),5(10),6,8,11,14,16,19(31),20,22(30), 23,25(29),26,28(32)-tetradecaene, 8. The ligand was synthesized via a condensation reaction involving 2,9-dimethyl-1,10-phenanthroline and 2,9-dicarbaldehyde-1,10 phenanthroline, followed by nickel metal complexation. Fourier-transformed infrared (FT-IR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, and thermal analyses were employed to characterize the ligand and its Ni complex. Their ADMET parameters and potential macromolecular targets calculations showed they have therapeutic potentials. The antioxidant assay shows that Ni-complex is approximately 9 times more potent than the ligand with IC50 values of 0.045 mg/ml and 0.404 mg/ml, respectively. Their microspecies distribution which was predicted using ChemAxon Predictor revealed their catalytic potentials The reaction mechanisms involved are discussed. The 1,10-phenanthroline-based macrocyclic ligand and its nickel complex significantly expand the structural diversity within the tetraza-macrocyclic ligand system and serve as base ligands for the development of possible derivatives, with concomitant applicability in drug development and catalysis.