Structure of the β-cyclodextrin: acetamiprid insecticide inclusion complex in solution and solid state

Abstract

The molecular microencapsulation process, through the formation of the inclusion complex with β-cyclodextrin (β-CD), shows numerous environmental and industrial cost advantages, such as, stability improvement of the active substance, synthesis of water-based products, option of commercializing the final product either in solid state or in solution and avoidance of the undesired side-effects derived from the use of insecticides. Furthermore, the inclusion complexes have other advantages that involve controlled and specific release of active component in the medium. In this work the synthesis of the inclusion complex formed by β-CD and the acetamiprid (ACET) nicotinoid insecticide ((E)-N1-[(6-chloro-3-pyridyl)methyl]-N2-cyano-N1-methyl-acetamidine) was done and their molecular structure was studied in solid state and in solution, by means of experimental techniques. The 2:2 stoichiometry found in solid state, a structure based on dimmers classified as a channel type, is similar to that found in solution (1:1 stoichiometry). In both cases, the nitrile and chloropyridine groups of the insecticide molecules are oriented toward primary rim and secondary rim of the β-CD molecule, respectively.