Polymeric ionic liquids with antimicrobial activity.

Polymeric ionic liquids (PILs) bearing imidazolium group have been extensively investigated as antimicrobial compounds due to their broad spectrum of activity and because do not easily induce bacterial resistance wìth low toxicity toward mammalian cells. With the aim to develop new antimicrobial compounds, we synthesized new ionic and polyionic liquids by metathesis reaction of 1-hexadecyl-3-methylimidazolium bromide, previously prepared by alkylation of 3-methylimidazole with 1-bromohexadecane, with different anions. The following compounds have been synthesized: 1-hexadecyl-3-methylimidazolium dimethyl-5-sulfoisophtalate (HDmim+ DMSIP-), 1-hexadecyl-3-methylimidazolium styrene sulfonate (HDmim+ SS-), 1-hexadecyl-3-methylimidazolium poly(styrene-styrene sulfonate 75:25) (HDmim+ PSS- 75:25) and 1-hexadecyl-3-methylimidazolium poly(styrene-styrene sulfonate 90:10) (HOmim+PSS- 90:10). In order to obtain PILs, two copolymers have been produced by reaction of styrene and sulfonate styrene mixed at different molar ratios (75:25 and 90:10) and then used as anions for the synthesis of polyionic liquids HDmim+ PSS- 75:25 and HDmim+ PSS- 90:10. All the synthesized compounds have been characterized by 1HNMR, MALDI, DSC and TGA analysis. The antimicrobial activity of cotton gauzes loaded with different concentrations of ionic and polyionic liquids was investigated by disk diffusion method. The synthesìzed compounds induced a good antimicrobial activity against both Gram positive (Listeria innocua and Bacillus subtilis) and Gram negatìve (Pseudomonas fluorescens) bacterial pathogens, thus resulting promising antimicrobial agents for future applications in different fields (medical, alimentary, textile, etc.).