Correction and removal of expression of concern: Enhancement of anti-leukemic potential of 2-hydroxyphenyl-azo-2'-naphthol (HPAN) on MOLT-4 cells through conjugation with Cu(ii).

[This corrects the article DOI: 10.1039/C3RA44765K.].

A Zn complex of ornidazole with decreased nitro radical anions that is still highly active on .

A monomeric complex of Zn with ornidazole [Zn(Onz)Cl] decreases formation of the nitro-radical anion (R-NO˙), and this is realized by recording it in an enzyme assay using xanthine oxidase, which is a model nitro-reductase. Although the formation of R-NO˙ is essential for drug action, as it is also associated with neurotoxic side effects, it is imperative to control its generation in order to avoid excess presence. With a decrease in R-NO˙, while the neurotoxic side effects should decrease, it can be expected that a compromise with regard to therapeutic efficacy will be seen since the complex will be less active in the free radical pathway.