Copper(II) complexes of usnic acid condensation products and their antibacterial activities

The complexes of Cu(II) and condensation products of usnic acid with the acyl hydrazides of α-naphthoic, caprylic and oxamic acid, as well as the derivative of usnic acid with thiosemicarbazide have been synthesized and characterized by elemental analyses, molar conductivity, magnetic moment measurements and IR spectroscopy. It was found that the derivatives act as tridentates occupying three coordination places in the square planar molecules with the fourth coordination site occupied by a solvent molecule. The complexes were tested for in vitro growth inhibitory activity against the bacterial species Escherichia coli and Staphylococcus aureus. The complexes have higher antibacterial activities compared to both the usnic acid derivatives and Cu(II) ions.