Study on the molecular recognition of herbicide quizalofop-p-ethyl with β-cyclodextrin

The molecular recognition behavior of quizalofop-p-ethyl (qpe) with β- cyclodextrin (β-cd) has been investigated quantitatively by uv-vis measurements. the stoichiometric ratios,stability constants and thermodynamics of inclusion reaction are determined. the results showed that β-cd could obviously enhance the water-solubility of qpe,which was favored to develop waterborne of the pesticide formulation. they could form 1:1 inclusion complexes and the formation constant reduced with the elevation of temperature,indicating that inclusion complex was unsuitable to be prepared at higher temperature. thermodynamic parameters of inclusion reaction (δh•δs•δg) were all negative•suggesting that interaction process between β-cd and qpe was spontaneous driven by enthalpy and entropy changes. the inclusion complex of qpe with β-cd was prepared by coprecipitation technique and characterized using infrared spectroscopy(ir),differential scanning calorimetry(dsc) and 1h-nmr spectroscopy,respectively. the 1h-nmr analysis in d2o revealed that the aromatics ring containing cl atom entered into the cavity of β-cd through the wider rim.