Bioinspired Herbicides-Ionic Liquids or Liquid Cocrystals?

Area of Science:

• Green Chemistry
• Agricultural Science
• Materials Science

Background:

• Phenoxyacetic acid herbicides, such as MCPA and 2,4-D, are widely used for weed control.
• Developing novel formulations of existing herbicides can enhance efficacy and potentially reduce environmental impact.
• Amino acids can be utilized as building blocks for creating new chemical entities with unique properties.

Purpose of the Study:

• To synthesize and characterize novel amino acid ionic liquids (AAILs) and amino acid liquid cocrystals (AALCs) using l-proline, l-arginine, and l-histidine with MCPA and 2,4-D.
• To elucidate the structural properties and hydrogen bonding characteristics of the synthesized compounds.
• To evaluate the herbicidal activity of the novel formulations compared to commercial standards.

Main Methods:

• Synthesis of five AAILs, one amino acid higher-melting salt (AAHMS), and two AALCs.
• Characterization using Nuclear Magnetic Resonance (NMR), Infrared (IR) spectroscopy, and X-ray crystallography.
• Computational analysis including molecular modeling, NBO, and QTAIM calculations for hydrogen bond energy estimation.
• Herbicidal activity assays.

Main Results:

• High yields (>90%) were achieved for the synthesized AAILs, AAHMS, and AALCs.
• Structural confirmation of ionization and hydrogen bonding was established through spectroscopic and crystallographic methods.
• AAILs were formed with arginine and histidine, while proline formed AALCs with MCPA and 2,4-D.
• The novel formulations exhibited improved weed control efficacy compared to commercial MCPA and 2,4-D formulations.

Conclusions:

• The study successfully synthesized and characterized new forms of MCPA and 2,4-D based on amino acid ionic liquids and liquid cocrystals.
• The structural analysis provided insights into the formation of these novel compounds and their hydrogen bonding networks.
• The developed formulations represent a promising advancement in herbicide technology, offering enhanced weed management capabilities.