Abstract: The conformations of the complexes which are formed in the interaction between chiral stationary phase(CSP) and diniconazole enantiomers have been optimized by molecular mechanics. Using molecular mechanics, we calculated the bond lengths, bond angles, dihedral angles and total energies of those complexes respectively. The results show that both R-and S-species of diniconazole can form complexes ( R-CSP and S-CSP) with chiral stationary phase by two hydrogen bonds. The hydrogen bonds of S-CSP are stronger than those of R-CSP. As compared with R-CSP complex, S-CSP complex is more stable, and has a longer retention time than R species in chiral separation. Based on the factor that there are high rotational barriers for the main single bonds in both R-CSP and S-CSP complexes, we can get the same conclusion as in experiments that the separation results have little changes with the temperature. The π-π interaction between R-or S-species of diniconazole and CSP was not found.

Key words: Chiral separation, Chiral discrimination, Diniconazole, Molecular mechanics