Nuclear magnetic resonance (1H) and13C), vibrational spectroscopy, and quantum chemical calculations (complete neglect of differential overlap/2 [CNDO/2]) have been used to investigate 20 biologically active title compounds, inhibitors of the dihydropteroate synthase. The data obtained have been comparatively analyzed by correlation and multivariate analyses. The results obtained show that also in the case of multisubstitution the electronic effect can be rationalized in terms of electronic charge perturbations which are transmitted from the multisubstituted aryl ring to the common biofunctional moiety 4-NH2—C6H4—SO2—trough the SO2group, mainly via hyperconjugation. Good predictions of both spectroscopic and biological data are obtained by the partial least squares method using quantum chemical descri