Conformation and biological activity of hydroxy-phenyl-ammonium compounds

Ab initio (STO-3G) and semiempirical (NDDO) quantum chemical methods were applied to some hydroxy-phenyl-ammonium compounds to investigate their conformational structure. It is demonstrated that the theoretical conformational analysis in combination with experimentally measured activity data of a small number of compounds may serve as a useful tool to optimize the biological active conformation, which does not correspond to the blobal minimum conformation in this group of molecules.