Synthesis and characterization of some arylhydrazone ligand and its metal complexes and their potential application as flame retardant and antimicrobial additives in polyurethane for surface coating

• Hydrazone ligand and its metal complexes have been prepared and characterized.
• The ligand and its metal complexes added physically into polyurethane coating.
• The metal complexes showed better flame retardant activity than the original ligand.
• The metal complexes showed better activity than the ligand against the same organism.
• Molecular modeling of the free ligand and its metal complexes has been calculated.

Hydrazones are versatile organic ligands and can be synthesized by condensation of hydrazides with carbonyl compounds (aldehydes/ketones). These compounds coordinate to the metal ions via azomethine nitrogen. Hydrazone Schiff's base ligands and their transition metal complexes possess a number of biological and flame retardant applications. Some selected divalent metal (CuII and NiII) complexes of hydrazone Schiff base ligand, namely o-methoxybenzaldehyde benzoylhydrazone (MBH) was synthesized and fully characterized by elemental analysis, FTIR, 1HNMR and mass spectra. This work summarizes the application of the prepared MBH ligand and its metal complexes. The prepared MBH ligand and its metal complexes were physically incorporated in polyurethane coating and evaluated for their flame retardancy and antimicrobial activity for surface coating. The flame retardancy of these materials was characterized by the limiting oxygen index (LOI) test. The antimicrobial activity of these materials was screened against Gram-positive bacteria, Gram-negative bacteria and fungi. The physical, mechanical and chemical properties were studied to ascertain any drawbacks. On the basis of experimental results of an oxygen index (LOI) and the biological activity, the synthesized MBH ligand and its metal complexes showed excellent flame retardancy and antimicrobial activity. In addition, the metal complexes were much more active than the original MBH ligand. Quantum chemical calculations were also performed by Semiempirical PM3 method to find the optimum geometry of the ligand and its metal complexes. The calculated pharmacokinetic parameters in silico, showed promising futures for application of the MBH ligand and its metal complexes as high antimicrobial potency agents.

The MBH ligand and its metal complexes showed excellent flame retardancy and antimicrobial activity. The metal complexes were much more active than the original ligand. The molecular modeling study revealed that molecular properties of MBH ligand and its metal complexes are biologically safe, active and fulfill Lipinski's rule of five.Figure optionsDownload as PowerPoint slide