A novel dicationic ionic liquids encompassing pyridinium hydrazone-phenoxy conjugates as antimicrobial agents targeting diverse high resistant microbial strains

Abstract

A focused library of new dicationic ionic liquids (DiILs) 6–41 appended pyridinium hydrazone and phenoxy side chain hybrids as counter cations were designed and synthesized, utilizing quaternization and metathesis reactions under both conventional and microwave irradiation. The novel DiILs 6–41 were fully characterized using different spectroscopic tools (1H, 13C, 19F, 11B, 31P NMR and mass spectra) and evaluated for their antimicrobial activity against diverse types of high resistant strains including two Gram-positive bacteria; methicillin-resistant Staphylococcus aureus (MRSA), Clostridium difficile, two Gram-negative bacteria; two Escherichia coli isolates, and Neisseria gonorrhea, and fungal strain; Candida albicans. The antibacterial screening was carried out by broth microdilution method and MIC values were reported as indicator of growth inhibition. They mostly exhibited antibacterial effect against MRSA and EC strains. The effect of the synthesized ILs on Gram-positive bacteria showed the phenoxy linker chain increases, the MIC values increases with more lethal effect due to the hydrophobicity parameter. This behavior was confirmed by the molecular dynamic simulation through the interaction with surface membrane as general mechanism of ILs. The dicationic ionic liquids are considered promising motifs for further investigations with focusing on the terminal hydrophobic adjuster.