Enhanced physicochemical properties and herbicidal activity of an environment-friendly clathrate formed by β-cyclodextrin and herbicide cyanazine

Abstract Cyanazine is usually dissolved in organic reagents during use due to the poor solubility in water. However, cyanazine residues in the environment may cause serious harm to the soil, water and human body, etc. In this study, clathrate of cyanazine-beta-cyclodextrin (cyanazine-β-CD) clathrate was synthesized via co-precipitation to enhance the water solubility, thermostability and herbicidal activity of cyanazine. Moreover, the X-ray diffraction, scanning electron microscope and Fourier transform infrared spectroscopy techniques were used to examine the clathrate. Results proved that cyanazine successfully entered the cyclodextrin cavity. Clathrate of cyanazine and β-CD was synthesized in a 1:1 stoichiometric ratio explored using the study of inclusion ratios. Besides, clathrate improved the water solubility of cyanazine, which was proved by the phase solubility study. The improvement of thermal stability was confirmed by thermogravimetric analysis. Furthermore, the biological activity studies indicated the clathrate had better herbicidal activity than cyanazine.