Title : α-Aminophosphonate–β-Cyclodextrin Complex as a Promising Plant Growth Biostimulant
Abstract:
α-Aminophosphonates are a significant class of organophosphorus compounds related to α-amino acids, where the carboxyl group is replaced by a phosphonate group. Due to their high chemical stability, balanced electron-donating and electron-withdrawing characteristics, and ability to interact with biomolecular targets, these molecules show a wide range of biological activities, including antibacterial effects, enzyme inhibition, and promotion of plant growth. However, their practical use is often limited by poor solubility and low bioavailability. In this study, a new fluorine-containing α-aminophosphonate - dimethyl((1H-imidazol-1-yl)(2-(trifluoromethyl)phenyl)methyl)phosphonate - was synthesized through a one-pot Kabachnik–Fields reaction involving imidazole, dimethyl phosphite, and 2-(trifluoromethyl)benzaldehyde in benzene with azeotropic removal of water. The selection of a CF₃ group and an imidazole fragment was driven by their ability to improve membrane transport, stabilize biologically active conformations, and enhance interactions with receptor-like targets.
To improve the solubility and bioavailability of the synthesized molecule, it was incorporated into the hydrophobic cavity of β-cyclodextrin (β-CD), a natural cyclic oligosaccharide possessing strong inclusion capabilities. The structures of both the free compound and its β-CD inclusion complex were confirmed using IR, ¹H NMR, and ¹³C NMR spectroscopy.
Biological testing was performed on seeds of spring wheat (variety “Kazakhstanskaya 10”). Treatment with the β-CD–aminophosphonate complex resulted in higher germination energy, increased seedling height, and improved overall plant health compared to the untreated control. The biostimulant effect is due to the combined properties of the fluorinated and heteroaromatic fragments, as well as β-cyclodextrin's capacity to improve the solubility, stability, and cellular transport of the active agent.
These results show that forming complexes of fluorinated α-aminophosphonates with cyclodextrins is an effective way to create environmentally friendly plant growth stimulants. Such systems have potential to improve crop stress tolerance and help maintain stable agricultural productivity amid changing climate conditions.
