Two dinuclear silver complexes containing 5,7-dimethyl[1,2,4]triazolo[1,5-a]pyrimidine (dmtp) were synthesized, [Ag2(dmtp)3]2[Ag2(dmtp)2](BF4)6(H2O)2 and [Ag2(dmtp)2(ClO4)2][Ag2(dmtp)2(H2O)2](ClO4)2. They have been spectroscopically and thermally characterized and their structures have been solved by single crystal X-ray diffraction. The compounds display fluorescence in the visible range (486 nm) when irradiated with UV light (265 nm). Both compounds, together with a previously reported analogue containing nitrate as counteranion, were assayed in vitro against three different species of Leishmania spp. and Trypanosoma cruzi, (parasites responsible for Leishmaniasis and Chagas disease) showing an extremely high antiparasitic activity, with IC50 values below the lower tested concentration (1 μM) for the three compounds and the four microorganisms, and hence a selectivity index better than those of the reference commercial drugs by more than one magnitude order, also improving the results of the free ligand and previously reported complexes with metals of the first transition series.
Keywords: Antiparasitic activity; Chagas disease; Leishmaniasis; Metal complexes; Silver; Triazolopyrimidines.
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