Conformer Study on 18-Crown-6

The scaled ab initio 6-31G* ESP charges for three kinds of eunformations (C-i, D-3d, C-1) of 18 crown 6 were calculated by MNDO. The conformation energies and structures were calculated by molecular mechanics. The results showed that the changes of charge-distribution in different conformations influenced the conformation energies significantly. Using the electronegative charges, the energies and structures were also obtained from molecular mechanics. The results were in good agreement with those using the MNDO scaling 6-31G* ESP charges. It suggested that the electronegativities could be used as the force field parameters in calculating various conformation energies in molecular mechanics and molecular dynamics.