Electrochemical and pH control of the complexation/decomplexation of 4-amino-N,N-diphenylamine with β-cyclodextrin

The behavior of the inclusion complex based on 4-amino-N,N-diphenylamine (ADPA) and cyclodextrin was studied by several techniques at different pH values and in different oxidation states. The results indicate that the reversible inclusion of the guest compound depends on its protonation state, and that its oxidation and reduction occur outside the cyclodextrin cavity. Moreover, the product of the guest bielectronic oxidation reaction is protonated and is free mainly, but in the presence of cyclodextrin and at neutral pH, it fits back into the cavity. This work shows that it is possible to control, by the pH and/or the applied potential, the complexation of ADPA or its oxidation product in a cyclodextrin cavity and gives information for synthesizing encapsulated conductive polymers based on a PANI like structure. (C) 2000 Elsevier Science S.A. All rights reserved.