The dyes Azo have a lengthy history and are a vital part of our daily lives. There are numerous potentials uses for these substances and their derivatives in various industries and environmental and biological research. In this study conversion of various azo compounds into other derivatives, complexes, and polymers was accomplished. This review included examining the chemistry reactions, synthesis, and applications of azo dye ligands and their complexes, mentioned spectral, analytical, thermal, and morphology methods of investigation, and confirmed by mass fragment mechanisms for some azo dyes and metal complexes. One of the aims of this review is to explain the role of these azo dye derivatives and the effect of metal complexes on leather which exhibits high light fastness, wash fastness, and rubbing fastness. The interaction of DNA has also been achieved. New metal complexes (Co (II), Ni (II), Cu (II), and Zn (II) azo ligands derived from 4-amino antipyrine and 4-aminoacetophenone are reported. The nature of the compounds has been studied followed by methods of continuous contrast, Beer's law, and molar ratio. Analytical methods and spectra revealed the octahedral geometry of the complexes. The azo dye ligand and its metal (II) complexes possess appreciable microbial activities. Novel heterocyclic compounds and its complexes have been investigated. The relationship between the HOMO-LUMO gap and antibacterial activity was investigated computationally. Improved understanding of binding mechanisms was shown by the comparative molecular docking investigations. This review demonstrated the utilization of the polycrystalline Zn (II) metal complex as a sensitizer in organic dye-sensitized solar cells. Quinolinyl-azo-naphthol (HL) is a selective turn-on chemosensor for Al3+ in the presence of other ions, exhibiting a 750-fold rise in emission at 612 nm following activation at visible light (537 nm). The reported limit of detection (LOD) for the 3σ technique is 0.69 nM. During this review it was proven that the effective production of palladium nanoparticles with guar gum as a stabilizer and their use as a catalyst in reduction processes and azo dye degradation. The investigation describing and assessing thiazolyl azo ligand complexes with specific metal ions has been presented.( Zn (II), Cu (II), Co (II), and Ni (II) ) complexes with azo ligands generated from metoclopramide hydrochloride were examined for their industrial and biological applications in cotton fabric dyeing, as well as for light and cleaner firmness. Additionally, the evaluation of the ligand and their complexes' antimicrobial and antifungal capabilities revealed that the ZnL molecule had the strongest antibacterial activity. The application characteristics of thiophene-derived dispersion dyes complexed with Zn, Cu, and Co metal on (polyester and Nylon 6.6), showed good to excellent light fastness, good to excellent wash fastness, excellent fastness to perspiration and sublimation, and good levelness on both materials with varying shades of brown and violet. The azo benzoic acid ligand derived from 2,4-dimethylphenol and 4-aminobenzoic acid has been identified by several spectroscopic methods and has been used as dispersion dyes on cotton textiles to test the antibacterial properties of the chemicals generated against a range of bacteria and fungus. Each primed complex has been proposed to have a tetrahedral geometrical structure for the obtained datum. There have been reports on the use of azo dyes in combination with nickel and its uses in dye-sensitized solar cells. Ten complexes of metals including Zn (II), Cu (II), Cd (II), Ni (II), and Co (II) as well as Phloroglucinol and antipyrine were used to create two unique azo-colorants, which were isolated and examined using a variety of techniques, wool, polyamide, and poly acetate fibers exhibit coloristic activity toward H3L1 and H3L2 as well as their metal complexes, demonstrating their strong resistance to UV radiation. Both in static and dynamic settings, the H3L2 compound exhibited a good sorption activity towards heavy metal cations from aqueous solutions of trace concentrations. A particular combination of selected transition metal ions is complexed with the azo compound, which is obtained from the (2-hydroxy quinoline: synthesis, characterization, thermal analysis, and antioxidant activity). These compounds' reactive oxygen entity degradation was evaluated with the DPPH radical and subsequently compared to gallic acid, a standard naturally occurring antioxidant. Finally, this review explains the metal chelates of the azo dye derivative sulfafurazole through synthesis, structure confirmation, molecular docking simulation, antibacterial, anticancer, and application in bioinorganic chemistry.
