Electrochemical evidence of host-guest interaction. Change of redox mechanism of fungicides iprodione and procymidone in the nano-cavity of cyclodextrins

The reduction mechanism of two pesticides, iprodione w3-(3,5-dichlorophenyl)-N-(1-methylethyl)-2,4-dioxo-1-imidazolidinecarboxamidex and procymidone w3-(3,5-dichlorophenyl)-1,5-dimethyl-3-azabicyclow3.1.0xhexane-2,4- dionex, was studied in the absence and presence of b-cyclodextrin in a dimethylsulfoxide solvent. Distribution of the reduction products changed in the presence of b-cyclodextrin. The complex formation led to protection of the imidazolidine ring of iprodione against cleavage, with a subsequent decrease in aniline-type products. In the case of procymidone, the mechanism exclusively led to the formation of monochloro derivatives of the original pesticide. Host–guest-type interactions of these pesticides with cyclodextrin nano-cavities was unambiguously demonstrated by voltammetric measurements that were more sensitive than conventional spectroscopic methods, such as UV-VIS and NMR.