Amino acid-based dicationic ionic liquids as complex crop protection agents

[Display omitted] •Amino acid-based dicationic ionic liquids were synthesized and characterized.•The structure of the cation determines the solubility and surface activity.•The prepared ionic liquids exhibited a deterrent activity.•Novel dicationic ionic liquids based on amino acids might replace toxic chemicals used to prevent insect feeding. The utilization of efficient synthesis methods and natural raw materials to obtain novel compounds with biological activity is crucial due to the requirement to reduce the negative effect on the environment. In this study, we responded to recent trends and developed a procedure to synthesize a new group of ionic liquids containing l-histidinate or l-prolinate anions and bis-ammonium or bis-phosphonium cations with an alkyl linker or with a linker containing two ester bonds. The structures of the obtained compounds were confirmed by performing spectral analyses (FT-IR, 1H and 13C NMR). Based on analyses of the effect of the obtained compounds on the deterrent activity against storage insects, the obtained ionic liquids exhibited at least weak deterrent activity and the length of the alkyl linker and the presence of an ester bond in the cation were essential determinants of biological activity. Furthermore, in the case of several salts, we observed significant positive effects on root system development and limited inhibition of shoot growth, indicating reduced phytotoxicity. Analyses of relevant physicochemical properties (differential scanning calorimetry, thermogravimetric analysis, surface activity, and solubility analysis) were performed to determine the effect of structure on the measured parameters. Furthermore, antimicrobial activity assays were performed to analyze the environmental effects of the products. Our results indicate a significant future potential use of these novel ionic liquids as agrochemicals.