The synthesis and characterization of the hydrazone ligand and its metal complexes and their performance in epoxy formulation surface coatings

Hydrazones are present in many of the bioactive heterocyclic compounds that are of wide interest due to their biological applications. This article focuses on the synthesis of the hydrazone ligand and its metal complexes and their potential application as anti-microbial, antifouling and flame retardant additives in epoxy formulations for surface coating application. Selected divalent (CoII) and trivalent (CrIII and FeIII) metal complexes of arylhydrazones, namely o-hydroxyacetophenone benzoylhydrazone (HBH) have been isolated and characterized by a combination of elemental analysis, FTIR, 1H NMR and mass spectra. The ligand and its metal complexes were physically added to an epoxy resin. Experimental coatings were produced on a laboratory scale, and then applied using a brush onto both wood and steel panels. Results obtained from an oxygen index value indicated that the epoxy resin containing the ligand (HBH) and its metal complexes as additives, exhibit a very good flame retardancy effect. The results of the biological activity indicated that the HBH ligand and its metal complexes exhibit a very good antimicrobial and antifouling effect, with the metal complexes showing better results than the ligand. Both physical and mechanical resistance properties were also studied, to evaluate any drawbacks due to the inclusion of the additives. The additives did not affect the flexibility, hardness and adhesion of the epoxy resin formula. The gloss was increased due to the incorporation of the aromatic ring, and the impact strength was also increased due to the incorporation of metal into the epoxy resin formulation.