This study is focused on the utilization of naturally occurring ascorbic acid (vitamin C) in the synthesis of biologically inspired ionic liquids with attractive application potential. The ionic liquids with the ascorbate anion were obtained in high yield (>90%) via a simple, "green" two-step procedure using well-known, cost-effective, and commercially available alkyltrimethylammonium, dialkyldimethylammonium, and alkylmethylbis(2hydroxyethyl)ammonium cations. Three positive ions in this group used for syntheses are derived from renewable resources, such as vegetable oil or animal fat. The study confirmed the strong influence of the chemical structure of the cation on the stability of the compounds obtained in the air, as well as in aqueous solutions. In addition, the synthesized ionic forms of vitamin C exhibited very good antibacterial and antifungal properties against different microorganisms, including pathogens. The tests also revealed the excellent or good deterrent activity toward common stored-grain insects (granary weevil, confused flour beetle, and khapra beetle), reaching the values determined for azadirachtin, known as the reference antifeedant. The best results were achieved with products containing two long alkyl substituents in the cation (dimethyldioctylammonium and didecyldimethylammonium) that proved to be extremely effective against all the organisms tested. The results of the biological activity indicate that the products synthesized belong to the third generation of ionic liquids. In conclusion, ascorbate-based ionic liquids with multifunctional (antibacterial, antifungal, antifeedant, and antioxidant) properties have substantial potential to be used in the storage of crop protection products.

The present study is focused on the utilization of naturally occurring abietic acid in the synthesis of high added-value compounds with attractive characteristics. The synthesis of ILs derived from abietic acid was conducted using ion-exchange or neutralization methods, and the products were obtained with high yields exceeding 85%. The study confirmed strong influence of the chemical structure on the physicochemical properties of the obtained compounds, such as solubility, thermal stability, and phase transitions. The results also revealed excellent deterrent properties of ILs with abietate anions toward S. granarius, T. conf usum, and T. granarium, reaching or exceeding the values calculated for azadirachtin. The best results were achieved for cations containing long alkyl substituentstetraalkylammonium and 1-alkyl-3-methylimidazolium cations. Additionally, the obtained compounds exhibited antioxidant properties in the DPPH radical scavenging assay. The highest activity was observed for tetraalkylammonium cations. The obtained results allow for a conclusion that abietate ionic liquids with both antifeedant and antioxidant activity can be successfully implemented into storage crop protection.

a This study was focused on presenting a new class of ionic liquids (ILs) with anions of natural origin. The salts were obtained by hydrolysis of defined triglycerides or edible vegetable oils (coconut oil and canola oil) by quaternary ammonium hydroxides. The basic physicochemical properties of the obtained products were studied and their microbial and deterrent activity was determined. Additionally, their susceptibility to biodegradation was evaluated. The described synthesis pathway utilizes vegetable oils and quaternary ammonium hydroxides as reactants in order to obtain ILs with anions of natural origin, which are characterized by specific biological activity. The majority of the prepared ILs exhibited excellent feeding deterrent properties and could be classified as readily biodegradable compounds. The employed method is characterized by low cost of substrates, high yields and high purity of the obtained products. It might potentially find application as a tool to synthesize environmentally-friendly ILs with attractive properties for a wide range of applications.

The results of biological tests showed that halogen atom removal significantly increased the antifeedant properties of γ-lactones with a p-methoxyphenyl substituent. Unsaturated lactones are most promising in the context of their possible industrial application as crop protection agents. Further structural modifications of lactones with aromatic rings are needed to find important structural factors increasing the antibacterial activity.

The synthesized “sweet” ionic liquids comprising acesulfame anion proved to be effective antifeedants with designer physicochemical properties.

In this study, new quaternary bis(ammonium) salts with alkyl-1,X-bis(dimethyldecylammonium) cation and saccharinate, acesulfamate, lactate and pyroglutamate anions were synthesized and characterized by 1H and 13C NMR spectroscopy. Thermal gravimetric and differential scanning calorimetry analyses confirmed that all salts were thermally stable and the majority of them exhibited melting points below 100 °C. The physicochemical properties (viscosity, density, refractive index values, and solubility) of the obtained salts were determined for three compounds with lactate anions. All the tested salts have suitable properties which, in practical application, will reduce the losses caused by the most important storage insects. Most of the synthesized ionic liquids had comparable or better deterrent activity than azadirachtin—an alkaloid known as the most active antifeedant.Graphical abstract Electronic supplementary materialThe online version of this article (10.1007/s11696-018-0495-6) contains supplementary material, which is available to authorized users.

Novel ionic liquids with cations based on alkyl derivatives of 1,4-diazabicyclo[2.2.2]octane (DABCO) and an anion derived from naturally occurring pelargonic acid possessed double biological functions: herbicidal and deterrent activity.

In this study, we demonstrate that quinine with confirmed antiviral and antifeedant activity can be derivatized and formulated as multifunctional ionic liquids which allow one to tune their biological, chemical, and physical properties. Following the optimization of quinine alkylation, pure 1-alkylquinine bromides with alkyl chain length ranging from ethyl to dodecyl were synthesized and extensively characterized. In the next step, these derivatives were combined with counterions of natural origin, which resulted in the formation of naturally derived ionic liquids. Our results indicate that the transformation of quinine into ionic liquids may improve antifeedant properties by 265% compared to the activity of quinine-free base. Moreover, unlike the majority of known cases, the reduction of the alkyl chain length results in a significant increase in this type of biological activity.