Synthesis, spectral, and in vitro antimicrobial studies of organosilicon(IV) complexes with Schiff bases derived from dehydroacetic acid

Some new di and tri-organosilicon complexes of type R2Si(L-1)Cl, R3Si(L-1), and R2Si(L-2)/R2Si(L-3) (R = Me, Et, Bu, and Ph; L-1 = 4-hydroxy-6-methyl-3-[1-(quinolin-8-ylimino)ethyl]pyran-2-one, L-2 = 3-[1-(2-aminophenylimino)ethyl]-4-hydroxy-6-methylpyran-2-one, and L-3 = 3-[1-(2-amino-4-chlorophenylimino)ethyl]-4-hydroxy-6-methylpyran-2-one) were synthesized from Schiff base ligands derived from 8-aminoquinoline/o-phenylenediamine/4-chloro-o-phenylenediamine with dehydroacetic acid. All the compounds were characterized with the help of molar conductance measurements, elemental analyses, UV-Vis, IR, H-1, C-13, Si-29 NMR, and mass spectroscopy. On the basis of all these studies, penta-coordinated environment around central silicon atom in 1:1 molar ratio was proposed. The ligands and their organosilicon complexes were tested in vitro for antibacterial activity against Gram-positive bacteria viz. Staphylococcus aureus, Bacillus subtilis as well as Gram-negative bacteria viz. Escherichia coli and antifungal activity against Aspergillus niger. Antimicrobial activity results indicated that biological activity of ligands was enhanced on complexation with organosilicon group and phenyl derivatives were found to be more effective antimicrobial agents as compared to other complexes. Further, docking simulation of four compounds against E. coli topoisomerase II DNA gyrase B were carried out.