Alternating current aspects of antimicrobial molecular complexes

A novel method was designed involving the titration of alternating current titration in a cell where one electrode was shielded by a capillary enclosu re restricting access to it by charge carriers. With this cell, charge tran sfer complex titration of several thiazines all with some antimicrobial pro perties was effected in acetonitrile, against the electron accepting molecu le iodine. The maxima of the Job plots generated by these titrations exhibi ted displacement of their positions for the forward and reverse titrations with respect to electron donor-acceptor complexation conductivity and appar ent stoichiometry. A plot of inverse conductivity maxima differences agains t literature-cited dipole moments squared yielded a straight line passing t hrough the origin. The titration plot profiles are discussed in terms of th e type, number, and mobility of charge carriers produced in the complexatio n interaction. This novel method may be used to determine dipole moments of bioactive homologues empirically. There was correlation between thiazine d rug dipole moments and minimal inhibitory concentrations of these drugs for some bacterial and yeast species. Several new avenues of investigation of possible relevance to microbiology are suggested. (C) 2000 Elsevier Science B.V. and International Society of Chemotherapy. All rights reserved.