Synthesis and biological evaluation of copper (II) complexes of sterically hindered o-aminophenol derivatives as antimicrobial agents

Cu(II) complexes with 4,6-di(tert-butyl)-2-aminophenol (I) and 2-anilino-4,6-di(tert-butyl)phenol (II) have been synthesized and characterized by means of elemental analysis, TG/DTA, FT-IR, UV–vis, ESR, and conductance measurements. The compounds I and II can coordinate in their singly deprotonated forms and behave as bidentate O,N-coordinated ligands; their CuL2 complexes are characterized by CuN2O2 coordination modes and square planar geometry. In vitro antimicrobial screening against Gram-positive and Gram-negative bacteria, yeasts, and moulds indicated that the compound I and its Cu(II) complex were more active than Questiomycin B, the compound II, and its Cu(II) complex.