Synthesis, characterization, DFT studies and evaluation of antimicrobial activities of 3-amino-1-(4-nitrophenyldiazenyl)- 4H-thieno[3,4-c]chromene-4-one coordination compounds with Ni(II), Co(II) and Mn(II) salts.

Synthesis, characterization, DFT studies and evaluation of antimicrobial activities of 3-amino-1-(4-nitrophenyldiazenyl)- 4H-thieno[3,4-c]chromene-4-one coordination compounds with Ni(II), Co(II) and Mn(II) salts.

Sopbue-Fondjo1* E., Atedjong-Tedjong1 V., Tchieda-Kougoum1 V., Atongo-Dassi1 E., Tamokou2 J. D. D., Siewe1 A. D., Djeukoua-Dimo1 K. S. Tonle-Kenfack1 I., Kuiate2 J. R.

1Department of Chemistry, University of Dschang, Dschang, Cameroon; 2Department of Biochemistry, Faculty of Science, University of Dschang, Dschang, Cameroon; *Correspondence to: sopbue@yahoo.fr

Background: For decades, people have been working hard to find solutions to a variety of problems on many levels. In medicine, the frequency and extent of infections caused by resistant bacteria have increased in both hospital and community settings. Fossil fuels, which are responsible for environmental pollution and the destruction of the ozone layer. With this in mind, we are investigating the synthesis of a new nickel Ni(II) metal complex (ATR1) with the ligand 3-amino-1-(4-nitrophenyldiazenyl)- 4H-thieno[3,4-c]chromene-4-one (VTR) with the aim of developing a new synthetic antimicrobial compound or photosensitiser in solar cells. Methodology: The required starting material was synthesised via a multicomponent condensation between sulphur, cyclohexanone and ethyl cyanoacetate according to the third version of the Gewald reaction. The metal chelate complex was obtained in good yield in ethanolic solution by reacting the compound with the nickel salt NiCl2.6H2O in a 1:2 (metal:ligand) molar ratio at 70 °C for 6 hours. The compounds VTR and ATR1 were characterised theoretically (density functional theory ”DFT”) and experimentally using IR and UV-Vis spectral data. In parallel these compounds were also tested on four bacterial strains: Staphylococcus aureus ATCC25923, Escherichia coli ATCC2592, Pseudomonas aeruginosa 4C76110 and Klebsiella pneumoniae 22. Result: The combination of the experimental and theoretical data thus obtained allowed us to reveal the presence of vibrational frequencies corresponding to the different chemical functions and transitions present in the compounds VTR and ATR1. These compounds presented an inhibitory effect on these bacterial strains and the DFT allowed us to have also the following energy gaps 2.68 eV for VTR and 0.91 eV for ATR1.Conclusion: The results show that the complex has better antibacterial and energetic properties than the corresponding ligand.

Keywords: 2-aminothiophene, complex, DFT.