Eco-friendly 2,4-D ionic cocrystal with enhanced release and reduced non-target losses

Abstract

The low solubility and high volatility of 2,4-D pose significant challenges for effective herbicide delivery and ecological harmony. Organic cocrystal engineering has gained prominence as a versatile method to improve pesticide properties, characterized by ease of preparation, proven effectiveness, low cost, and scalability. In this work, we report an organic ionic cocrystal of 2,4-D with DL-proline, where both molecules self-assemble through hydrogen bonding in the crystal lattice, with DL-proline maintaining its zwitterionic form. Compared to pure 2,4-D, the cocrystal reduces volatility by over 70 % while exhibiting excellent stability at room temperature. Furthermore, the cocrystal enhances the release profile of the active compound across a range of temperatures (15 °C, 25 °C, 35 °C), with a solubility increase of more than 2.8-fold. Moreover, the cocrystal reduces the evaporation rate of the solution, leading to a longer retention time on leaf surfaces. In terms of herbicidal efficacy, the cocrystal provides equivalent weed control at just 1/4 of the dosage required for pure 2,4-D. Additionally, it exhibits reduced toxicity to zebrafish and human hepatocytes and cardiomyocytes. This work underscores the significant potential of organic cocrystal engineering in improving multiple herbicide properties and highlights its relevance for the development of advanced agrochemical products.