Synthesis, characterization, and reactivity of the stable iron carbonyl complex [Fe(CO)(N4Py)](ClO4)2: photoactivated carbon monoxide release, growth inhibitory activity, and peptide ligation.

Photoactivated carbon monoxide (CO) release by the iron carbonyl complex [Fe(II)(CO)(N4Py)](ClO(4))(2) (1) is described. Compound 1 is a low-spin ferrous complex that is highly stable and soluble in aerobic aqueous solutions. CO release was studied by the substitution of MeCN for CO, which displays saturation kinetics, and by the transfer of CO to deoxymyoglobin, which is slow in the dark but fast upon irradiation with UV light (365 nm). Compound 1 is active against PC-3 prostate cancer cells and shows potent photoinduced cytotoxicity. In addition, the iron carbonyl complex was attached to a short peptide toward the goal of tissue or cell-specific delivery.

Iron-binding and mobilization from ferritin by polypyridyl ligands.

Polypyridyl ligands were investigated for their ability to bind and mobilize iron(ii) from ferritin in aqueous solution. Association constants with iron(ii) (pFe(II)) were determined for the pentadentate ligands N4Py (pFe(II) = 14.4) and Bn-TPEN (pFe(II) = 13.7) using a competition method with the hexadentate ligand TPEN (pFe(II) = 14.6, 0.1 M KNO(3)). Ferrous complexes were formed using the polypyridyl ligands and ferritin as the sole iron source in the presence of reductant. The observed rates of iron mobilization from ferritin were dependent on reductant and were higher in the presence of ascorbate than dithiothreitol. TPEN, N4Py and Bn-TPEN demonstrated comparable and in some cases faster rates and higher levels of iron mobilization when compared to the iron(ii) chelator 1,10-phenanthroline, particularly at low concentrations of chelator.