Synthesis, characterization,biological evaluation and molecular docking studies of salicylidene-aniline and their metal mixed ligand complexes with caffeine

Abstract

Salicylidene-aniline (HL) Schiff base was synthesized by the condensation of salicylaldehyde and aniline in basic media and its structure was characterized by IR, UV–Visible, NMR and DFT. The mixed Schiff base and caffeine complexes [M(L)2(caf)2] with M= Cu(II), Ni(II), Cd(II) and Zn(II), and caf= caffeine, were prepared and characterized by molar conductance, IR, UV–Visible 1H and 13C NMR and TGA/DTA. The ligand (HL) chelates through the (N and O) donors and caffeine coordinates through N9 to the metal ions, respectively. The molar conductance reveals that the metal complexes are non-electrolytes. The antimicrobial activity of the complexes has been tested against eight pathogenic bacteria and four fungi species. The obtained results show that metal (II) complexes exhibited moderate-to-good antimicrobial activity against several bacterial and fungal strains. The molecular docking shows that the mixed Schiff base caffeine complexes have good affinity with the protein kinase (CK2).