Synthesis, characterization, thermal properties, and biological evaluation of azo-transition metal complexes

The coupling reaction between tryptamine and 8-hydroxyquinoline led to the formation of a new azo ligand. The synthesized ligand was characterized using CHN, FT-IR, UV-Vis, and NMR spectroscopic techniques. Complexes of the ligand with VO2+, Cr3+, Mn2+, and Mo6+ ions were prepared in a (1:2) ratio, with the general formula [M(L)2]. The obtained complexes were characterized using flame atomic absorption, CHN analysis, FT-IR, and UV-Vis spectroscopy, in addition to magnetic susceptibility and conductivity measurements. The findings suggest that the ligand functions as a bidentate, with the complexes exhibiting octahedral, square planar and square pyramidal geometries. All the complexes were identified as non-electrolytes. Their antioxidant effectiveness in neutralizing free radicals was assessed using DPPH as the free radical and Gallic acid as a standard. The IC50 value was determined, revealing that the Mn-complex demonstrated stronger free radical inhibition ability. The antioxidant capacity of the complexes varied based on their IC50 values; the Mn-complex was found to have a higher ability to inhibit free radicals, and the ability to inhibit the complex varied according to the IC50 value. The results were as following Gallic acid ˃ [Mn(L)2(H2O)2] ˃ Ligand ˃ [Mo(L)2O2] ˃ [VO(L)2] ˃ [Cr(L)2H2OCl]. KEY WORDS: Tryptamine, 8-Hyrroxyquonoiun, DPPH, TGA analysis, Azo dyes compound Bull. Chem. Soc. Ethiop. 2025, 39(11), 2093-2107. DOI: https://dx.doi.org/10.4314/bcse.v39i11.2