ENANTIOMERIC RESOLUTION OF SULFOXIDES ON A DACH-DNB CHIRAL STATIONARY-PHASE - A QUANTITATIVE STRUCTURE-ENANTIOSELECTIVE RETENTION RELATIONSHIP (QSERR) STUDY

The interaction mechanism of a variety of racemic alkyl aryl sulfoxide s with a pi-acid HPLC stationary phase containing N,N'-(3,5-dinitroben zoyl)-trans-1, 2-diaminocyclohexane chiral selector was investigated b y means of quantum-chemical calculations (MNDO), partial least squares (PLS) analysis, and 3D comparative molecular field analysis (CoMFA). Quantitative structure-enantioselective retention relationships (QSERR ), were derived which have yielded significant insights into physicoch emical properties primarily responsible for chiral recognition. The in crease in retention (k') is favored especially by the analyte pi-basic character, accounted for by the sum of the electrophilic superdelocal izabilities of all aromatic carbon atoms (S(Ph)HOMO), and to minor ext ent by the H-bond basicity of the sulfoxide oxygen and the hydrophilic ity of solutes. In contrast, the separation factor (alpha) varied main ly with the steric properties of the substituents and with polar and e lectrostatic properties of the sulfoxide group. A 3D-QSERR analysis us ing CoMFA methodology has provided a more complete description of fact ors responsible for chiral recognition and has proven to be a useful t ool to examine differences in noncovalent fields (both the electrostat ic and the steric) mostly associated with variations of enantioselecti vity. (C) 1993 Wiley-Liss, Inc.