Bifunctional Double-Salt Ionic Liquids Containing both 4-Chloro-2-Methylphenoxyacetate and l-Tryptophanate Anions with Herbicidal and Antimicrobial Activity.

The goal of this research was to obtain and characterize ionic liquids based on a bisammonium cation and both 4-chloro-2-methylphenoxyacetate (MCPA) and l-tryptophanate anions. The concept of including two structurally different anions was utilized to achieve improved biological activity, while crucial functional traits could be designed by modifying the cation. The synthesis process was efficient and resulted in high yields. Subsequent analyses (nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy, and high-performance liquid chromatography (HPLC)) confirmed the chemical structure, purity, and molar ratio of ions in the obtained compounds. The described compounds are novel and have not been previously described in the literature. Evaluations of physicochemical properties indicated that the obtained double-salt ionic liquids (DSILs) exhibited high thermal stability, high solubility in water, and surface activity. A biological activity assessment using greenhouse tests revealed that the herbicidal efficiency of the studied DSILs was notably increased compared to the reference commercial herbicide (even by ∼50% in the case of oilseed rape), which could be attributed to their high wettability toward hydrophobic surfaces. The compounds also efficiently inhibited the growth of several microbial species, with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)/minimum fungicidal concentration (MFC) values at the level of several µg·mL-1. The length of the spacer and alkyl substituent in the cation notably influenced the physicochemical and biological properties of the DSILs, which allowed us to design the structures of the obtained compounds in accordance with needs. The presented results confirm the high application potential of the described DSILs and provide a new and promising path for obtaining new and efficient plant-protection agents.

Synthesis and Characterization of Double-Salt Herbicidal Ionic Liquids Comprising both 4-Chloro-2-methylphenoxyacetate and trans-Cinnamate Anions.

The synthesis and characteristics are presented of novel double-salt herbicidal ionic liquids (DSHILs) that contain 4-chloro-2-methylphenoxyacetate and trans-cinnamate anions. In the designed synthesis, an anion of natural origin and a herbicidal anion were combined with an amphiphilic bisammonium cation to obtain new DSHILs with high herbicidal activity while high biocompatibility is maintained. The NMR and HRMS spectral analysis confirmed that the target structures were formed. Furthermore, HPLC analyses indicated that, as assumed, both anions were present in equimolar amounts. Experiments regarding the herbicidal effectiveness confirmed that the synthesized DSHILs exhibited high biological activity. The solutions of DSHILs applied during greenhouse studies were characterized by a low contact angle (approx. 55-67°) and surface tension (approx. 32-35 mN m-1 ), which facilitated the contact of the active substance with the plant surface and penetration of the herbicide into the plant tissues.