Síntese, caracterização e estudo biológico de complexos de Ag(I) com N-acilidrazonas derivadas de aldeídos naturais e isoniazida

Abstract

In the present work, syntheses and characterizations of the salizid, o­vanizid, m­vanizid and p­vanizid ligands and their respective silver complexes in the ratio 1:2 (M:L) have been described. All compounds were analyzed by analytical methods, spectroscopic techniques, such as 1H and 13C NMR and by X­ray diffraction, All compounds were analyzed by analytical methods, spectroscopic techniques such as 1H and 13C NMR and by X­ray diffraction, but only for the complex [Ag(o­vanizid)2(NO3)].H2O was obtained the pure crystalline structure, through single crystal and polycrystalline methods. The Ag(I) coordination of all the synthesized complexes occurs by the nitrogen atom of the pyridine ring, and even considering the absence of crystallography model for Ag(m­vanizid) and Ag(p­vanizid) complexes the obtained results of IR and 1H and 13C NMR spectroscopic analyzes corroborate the coordination about silver(I) ions through N of the pyridine moiety. The [Ag(o­vanizid)2(NO3)].H2O crystalline structure has been solved by X Ray diffraction in both monocrystal and polycrystalline methods. The structure obtained by powder diffraction belongs to triclinic system and P­1 space group while the single­crystal method provide us a structure in orthorhombic system and Pbcn as space group. However, the basic structure is the same in both models. It was also observed that the structures obtained by these two methods of diffraction are differentiated by the type of coordination, since in the polycrystalline form there is a nitrate ion coordinated to silver. However in monocrystal form, the nitrate ion does not coordinate with silver. Thus, it can be said that this is a coordination isomerism case. Biological assays, in vitro, were performed for all the compounds synthesized, in which the minimum inhibitory concentration (MIC90) of compounds against Mycobacterium tuberculosis H37Rv (ATCC 27294) was determined. Higher antibacterial activities against M. tuberculosis were found when the compounds have substitutions in the 1,3 (meta) and 1,4 (para) positions in comparing with ortho (1,2) position in the aromatic ring, showing MIC90 below than 0.09 mg/L.