Dicationic ionic liquids as new feeding deterrents.

ABSTRACT: 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.

Bioinspired Herbicides-Ionic Liquids or Liquid Cocrystals?

This research provides information about combinations of several amino acids, including l-proline (Pro), l-arginine (Arg), and l-histidine (His), with phenoxyacetic acid herbicides (MCPA and 2,4-D). Five amino acid ionic liquids (AAILs), one amino acid higher-melting salt (AAHMS), and two amino acid liquid cocrystals (AALCs) were obtained in high yields (>90%). The ionization of the six new structures was confirmed by NMR, IR, and molecular modeling. X-ray crystallography was used to definitively confirm the binding location of the mobile hydrogen. Furthermore, we propose a computational method for estimating the energy of specific hydrogen bond(s) in AAIL crystals based on the NBO and QTAIM hydrogen bond parameters obtained by model calculations. An in-depth analysis of the structures allowed to answer the question posed in the title, ionic liquids or liquid cocrystals? AAILs based on arginine and histidine were obtained. In contrast, combining proline with MCPA and 2,4-D led to AALCs. Finally, the compounds were analyzed to measure their herbicidal activity. These studies proved that the novel form of MCPA or 2,4-D improved its ability to control weeds compared to commercial formulations containing the same active ingredients.

Dicamba-Based Herbicides: Herbicidal Ionic Liquids versus Commercial Forms.

Dicamba is a widely applied herbicide for crop protection and has potential for volatility. New formulations containing dicamba with greatly reduced volatility, introduced to the market in 2017, still caused foliar injury to crops and other plants in Arkansas and neighboring states in the United States. In response, we proposed the transformation of dicamba into protic as well as aprotic dicamba-based organic salts called herbicidal ionic liquids (HILs). All of the HILs were characterized by high stability, whereas the biological activity of the most effective products, evaluated during greenhouse studies, was found to be greater than that of currently used commercial analogues. Furthermore, the possibility of introducing an alkyl chain of a specific length allows one to obtain plant protection products with the desired physicochemical properties while maintaining herbicidal effectiveness. These studies are expected to aid in the design and development of new herbicidal formulations, which, depending on the weed species, could increase the efficacy of the applied active ingredient. Simultaneously, the volatility of the synthesized compounds, particularly those containing quaternary ammonium cations, was multiple times lower than that of the free acid of dicamba. This strategy minimizes the risk of off-site movement via volatilization, which may cause significant damage to neighboring broadleaf crops and pose a threat to existing ecosystems.