Synthesis, Characterization and Photoinduced CO Release by Manganese(I) Complexes

Herein, we report the CO release activity of three new photoCORMs, two with nonbonding pyridine moieties and one with a benzyl group. The compounds [MnBr(CO)3(bpa-κ2)] (2, where bpa = N-benzyl(2-pyridylmethyl)amine); [MnBr(CO)3(pmpea-κ2)] (3, where pmpea = N-(2-pyridylmethyl)-N’-(2-pyridylethyl)amine) and [MnBr(CO)3(bpea-κ2)] (4, where bpea = N-bis(2-pyridylethyl)amine) were synthesized and characterized by common spectroscopic techniques (UV-Vis, IR). Density functional theory studies were also performed to provide new insights into the M–C bond and to assume the orbitals involved in the absorption transitions. Their CO release activities were measured both in organic and in physiological media and compared to that of a previously published compound [Mn(CO)3(dpa-κ3)]Br (1, where dpa = N-bis(2-pyridylmethyl)amine). An increase in the number of members of the chelate from five to six, influenced the release of CO, affecting both the binding mode of the ligand and the CO release process and affecting their potential use as potentials CO release carriers as therapeutic agents.