Molecules formed by two pharmacophoric synthons--4-H2N--C6H4--SO2NH--and 2,4-diaminopyrimidine--were prepared. These structural units, with sulphamidic and antifolic action respectively, are bound without mutual electronic interaction, as demonstrated by their experimental electronic indices. The compounds were tested for activity on several bacterial strains and their biological activity was compared with that of molecular combinations formed by 4-aminobenzensulphonamide and substituted 2,4-diaminopyrimidines, to discover whether these two pharmacophoric synthons, so bound, are synergic.