SYNTHESIS, ANTIMICROBIAL TEST AND THEORETICAL STUDY OF 3-((6-HYDROXY- [1,1′-BIPHENYL]-3-YL)DIAZENYL)-4H-THIENO[3,4-C]CHROMENE-4-ONE AND ITS Ni(II) COMPLEX

For a long time, men have faced two major problems. From an environmental point of view, we have pollution linked to the use of fossil energies and from a health point of view, the proliferation of microbes. To deal with these two problems, researchers are constantly looking for new molecules with extraordinary properties. It is in this perspective that the azoic ligand was synthesized. The complex (4) was prepared by reflux complexation reaction and for 6H of the ligand with Ni.Cl2.6H2O (nickel chloride Hexaaqua). The structural, electronic and optical properties of the compounds were evaluated using the Density Functional Theory (DFT) method with the Becke 3-parameters Lee-Yan-Par (B3LYP) functional, in basis 6-31G(d,p) for the ligand and Los Alamos National Laboratory Two Double Zéta (LanlD2Z) for the complex. The in vitro antimicrobial activity of the synthesized compounds was evaluated against four bacterial strains (Escherichia coli ATCC25922, Salmonella typhi ATCC1408, Enterococcus faecalis ATCC 29212 and Pseudomonas aeruginosa 4C76110) and ciprofloxacin was used as reference antibiotic. The values of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) have been determined.
Compounds 3 and 4 were characterized using IR and UV-visible spectroscopy and theoretical simulations. Biological results showed that the compound (3) with MIC values between 32 and 64 μg/mL has moderate activity against Escherichia coli ATCC25922,, Salmonella typhi ATCC1408 and Enterococcus faecalis ATCC 29212. On the other hand, the compound (4) with MIC between 16 and 64 μg/mL also has moderate activity vis-à-vis all strains of bacteria tested and the greatest activity was observed on Escherichia coli ATCC25922 (MIC = 16). The study of the boundary molecular orbitals of the ligand and the complex to show that the complex has a lower energy gap than the ligand. The study of the molecular electrostatic potential and the indices of global reactivity to show that the complexation to create a more reactive entity than the starting ligand with the appearance of new nucleophilic sites.
It emerges from this study that the complex obtained had a higher activity than the ligand, a lower energy gap than that of the ligand, and a greater nucleophilic character compared to that of the ligand. Complexation has created a more reactive and biologically active entity. On this basis we can say that we have a promising result.
The complexation of azo derivatives with metal salts could be an alternative for preparing new antimicrobial compounds and new photosensitizer compounds.