A molecular mechanics study of 1:1 complexes between azobenzene derivatives and β-cyclodextrin

Azobenzene derivatives in solution present thermal cis-trans isomerization through the double bond -N=N-. Experimental results showed that P-cyclodextrin inhibited the isomerization process for some azoderivatives while others were not affected. As previous model studies on the inclusion complexation of cyclodextrins with various guests, offered significant insights into the non-covalent intermolecular interactions and theoretical calculations helped to illustrate the driving forces for the complexation, here we have undertaken a theoretical study of the entire process of the formation of 1:1 stoichiometry azobenzene/beta -cyclodextrin structures, in order to contribute to the understanding and rationalization of the experimental results reported before. With this purpose, we first searched for a possible way of formation of each substituted azobenzene/beta -cyclodextrin inclusion complex and then we have performed an analysis of the strain energy changes involved and we have also analyzed the interaction forces driving towards the different kinds of stable structures yielded by the calculation procedure. (C) 2000 Elsevier Science B.V. All rights reserved.