Physicochemical properties and fungicidal activity of inclusion complexes of fungicide chlorothalonil with β-cyclodextrin and hydroxypropyl-β-cyclodextrin

Chlorothalonil (CHT) suffered from its poor water solubility, which limited the application of CHT and might cause environmental pollution due to the use of organic solvents. In our research, inclusion complexes of hydroxypropyl-β-cyclodextrin (HPβCD) and β-cyclodextrin (β-CD) with CHT were formed to investigate the effect of β-CD and HPβCD on the water solubility, antifungal activity and thermal stability of CHT. The structure and characteristics of the two inclusion complexes were systematically evaluated by nuclear magnetic resonance (1H NMR), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermal gravity analysis (TGA). The results of 1H NMR, FT-IR, SEM and XRD indicated that CHT successfully entered the cavity of β-CD and HPβCD. TGA results proved that the thermal stability of CHT was significantly improved. Molecular modelling demonstrated that cyclodextrin could effectively complex with CHT. In addition, the biological activity test showed that the complexes had better antifungal activity than original CHT. Our research can provide useful information for the more reasonable use of CHT, and cyclodextrin can be more used in agriculture to improve the characteristics of pesticides.