Redox-active antifungal cobalt(II) and copper(II) complexes with sterically hindered o-aminophenol derivatives

Co(II) complexes with 4,6-di(tert-butyl)-2-aminophenol (HLI) and 2-anilino-4,6-di(tert-butyl)phenol (HLII) have been synthesized and characterized by means of physico-chemical methods. The compounds HLI and HLII coordinate in their singly deprotonated forms and behave as bidentate O,N-coordinated ligands; their low-spin Co(II) complexes are characterized by CoN2O2 coordination modes and square planar geometry. Both the free ligands and their Co(II) and Cu(II) complexes (we have produced and characterized the latter before) exhibit a pronounced antifungal activity against Aspergillus niger, Fusarium spp., Mucor spp., Penicillium lividum, Botrytis cinerea, Alternaria alternata, Sclerotinia sclerotiorum, Monilia spp., which in a number of cases is comparable with that of Nystatin and Terbinafine or even higher. The reducing properties of the ligands and their metal(II) complexes, as well as their antifungal activities, were found to decrease in the order: Cu(LI)2 > Cu(LII)2 ⩾ Co(LI)2 > Co(LII)2 > HLI > HLII.

Co(II) complexes with 4,6-di(tert-butyl)-2-aminophenol (R = H) and 2-anilino-4,6-di(tert-butyl)phenol (R = Ph) have been synthesized and characterized. The reducing properties of the ligands and their Co(II) and Cu(II) complexes, as well as their antifungal activities, were found to decrease in the order: Cu(LI)2 > Cu(LII)2 ⩾ Co(LI)2 > Co(LII)2 > HLI > HLII.Figure optionsDownload as PowerPoint slide