Conformational analysis of a tetrabenzylated dihomooxacalix[4]arene. A theoretical study

In the present paper we have performed a conformational analysis of the tet rabenzyl ether of the p-tert-butyldihomooxacalix[4]arene by molecular mecha nics/molecular dynamics simulations. These calculations indicate that among the six studied conformations, the 1,3-alternate is the thermodynamically most stable conformation, followed by the partial cone A, while the cone is the least stable conformation. Analysis of the energy components of the po tential energy shows that these preferences are mainly due to coulombic rep ulsion interactions between the oxygen atoms as well as to non-bonded steri c hindrance between the bulky groups. Molecular dynamics results also indic ate that, although all the six conformations are flexible with the phenol r ings twisting around from inward to outward pointing, they lie in geometrie s close to the starting ones and no conformational interconversions were de tected. (C) 1999 Elsevier Science B.V. All rights reserved.