Influence of structural changes of cation and anion on phytotoxicity of selected surface active ionic liquids

Abstract

In this study, the influence of the structural modifications of 10 surface active ionic liquids (SAILs), on toxicity towards wheat and barley germination and early growth was examined. First, SAILs containing 1,3-dialkylimiadzolium cation (1-dodecyl-3-methylimidazolium bromide, 1-dodecyl-3-ethylimidazolium bromide and 1-butyl-3-dodecylimidazolium bromide) were studied, followed by the study of SAILs containing methyl-pyridinium cation with the different position of the methyl group on pyridinium ring (N-dodecyl-2-methylpyridinium bromide, N-dodecyl-3-methylpyridinium bromide and N-dodecyl-4-methylpyridinium bromide). Furthermore, for the 1-dodecyl-3-methylimidazolium cation, the anion was changed from bromide to benzoate and hydroxybenzoate anions and the –OH group position on benzoate ring was varied (1-dodecyl-3-methylimidazolium benzoate, 1-dodecyl-3-methylimidazolium ortho-hydroxybenzoate, 1-dodecyl-3-methylimidazolium meta-hydroxybenzoate, 1-dodecyl-3-methylimidazolium para-hydroxybenzoate). The results showed that germination of both wheat and barley was decreased intensively with the increase in SAILs concentration. Moreover, the results demonstrated that the length of the longer alkyl substituent on the cation head has the most important role in toxicity, while change of the cation ring as well as the change in anion structure of the studied SAILs did not show a significant influence on germination of wheat and barley seeds and biomass reduction of young plants.