Copper (II) complexes of sterically hindered o-diphenol derivatives: Synthesis, characterization and microbiological studies

Abstract

Cu (II) complexes with the sterically hindered diphenol derivatives 3,5-di(tert-butyl)-1,2-benzenediol (I), 4,6-di(ter t-butyl)-1,2, 3-benzenetriol (II) and the sulfur-containing 4,6-di(tert-butyl)-3-(2-hydroxyethylsulfanyl)-1,2-benzenediol (III) and 2-[4,6-di(tert-butyl)-2,3-dihydroxyphenylsulfanyl]acetic acid (IV) have been synthesized and characteri zed by elemental analysis, TG/DTA, FT-IR, ESR, XPS, XPD and conductivity measurements. Compounds I-III can coordinate in their singly deprotonated forms and act as bidentate ligands. These compounds yield Cu (II) complexes of the stoichiometry Cu(L)2, which have square planar geometry (g∥ > g⊥ > ge). Unlike them, compound IV behaves as a terdentate ligand, and its complex Cu(LIV) 2 has d istorted octahedral geometry. According to ESR data, only the Cu(LII)2 complex contains a very small amount of phenoxyl radicals. Antimicrobial activities of these ligands and their respective Cu (II) complexes have been determined with respect to Gram-positive and Gram-negative bacteria, as well as on yeasts. Their phytotoxic properties against Chlorella vulgaris 157 were also examined. © Versita Warsaw and Springer-Verlag Berlin Heidelberg 2006.