MODELING OF THE SODIUM COMPLEX OF A CALIXARENE TETRAESTER IN THE 1,3-ALTERNATE CONFORMATION

This paper describes the use of molecular mechanics to model the geome try of the sodium complex of a calix[4] arene tetraester, in the 1,3-a lternate conformation 1. Partial charges were assigned to the calixare ne on the basis of semi-empirical (AM1, PM3, MNDO, INDO, CNDO and ZIND O) calculations and the binding of the sodium ion to the calixarene wa s modelled using molecular mechanics. Agreement between the optimised and X-ray structures of the complex was very good. The effect of placi ng the cation in different starting positions on the energy-minimised geometry of the complex is described.