From Plant Material to Environmentally Friendly Plant Growth Stimulators: Betaine-Based Ionic Liquids

Following global trends, the main issue is to ensure that humanity can progress without harming the environment. This article outlines the synthesis of novel ionic liquids composed of an alkylbetaine cation, whose structure is based on glycine-betaine (a byproduct of sugar beet production) and an anion based on indole-3-butyric acid (a natural auxin found in plants). The article details the synthesis method used and demonstrates its negligible environmental impact. In addition, the main physicochemical properties of ionic liquids and their initial substrates have been assessed. Biological studies indicate that these ionic liquids effectively stimulate plant growth compared to the potassium salt of indole-3-butyric acid by approximately 40-60%, promoting positive effects on plant growth after sowing, while they may also contribute to seed protection before sowing. Furthermore, environmental studies have shown that these compounds are unlikely to pose a threat to freshwater and saltwater organisms, as they fall into the Practically Nontoxic to Slightly Toxic class in the case of <i>A. franciscana</i> and the Practically Nontoxic to Moderately Toxic class in the case of <i>D. magna</i>. Moreover, ionic liquids exhibited a benign effect on soil microorganisms, with toxic effects occurring only for salts containing the longest alkyl chains (MIC = 62.5-250 μg·cm^-3).