Methyl-substituted 4-nitropyridine N-oxides as ligands: Structural, spectroscopic, magnetic and cytotoxic characteristics of copper(II) complexes

The IR spectra showed that the strength of the Cu-ligand bond gauged by the degree of N-O elongation changed irregularly with position and number of methyl groups. Cytotoxic studies on the MCF-7 human breast cancer line revealed a structure-activity relationship: double blocking of the NO2 group with two CH3 groups rendered the complex completely inactive.