Investigation of mesalazine-cobalt(III) complexes for hypoxia-activated prodrug development.

[Display omitted] • CoIII complexes have been designed for hypoxia-selective anticancer drug delivery. • Redox potential of CoIII-mesalazine complexes has been tuned by ancillary ligands. • Ascorbate successfully simulate biological redox activation. • O 2 -dependent dissociation of the mesalazine has been achieved upon Co3+/Co2+ reduction. Cobalt(III) complexes have been designed to coordinate and selectively deliver bioactive molecules to hypoxic regions of solid tumors. In this way, we report the synthesis, electrochemistry and spectroscopic properties and reactivity of three mesalazine-cobalt(III) complexes. An effect of the donor/acceptor capabilities of the ancillary ligands (py 2 en, me 2 py 2 en and tpa) was observed. Co3+/Co2+ potentials of all complexes are within the expected range for reduction/oxidation under biological conditions. An O 2 -dependent dissociation of mesalazine was observed for complexes 1 and 2 upon reduction by ascorbic acid. [ABSTRACT FROM AUTHOR]