Experimental and quantum chemical calculations of novel photoactivatable manganese(I) tricarbonyl complexes

[MnBr(CO)₃(TZ)] (1) and [Mn(CO)₃(MZ)] (2) (TZ = Tazarotene and MZ = Metamizole) have been synthesized and characterized as new visible light photo-trigged carbon monoxide releasing molecules. The ability to deliver CO to DMSO or myoglobin solution has been studied. TZ behaves as a bidentate ligand via the pyridine N-atom and [Formula presented] group, while MZ is a mono-negatively tridentate ligand and coordinates to Mn(I) through the pyrazolone [Formula presented], –SO₃⁻and tertiary amino groups. These photoCORMs cannot be stored for a long time in DMSO, but they are able to release CO fast upon the exposure to the light (412–468 nm). About one CO equivalent was delivered from CORM 1 to the myoglobin solution upon the exposure to 468 nm LED lamp for 42 min. The electronic configuration of the metal center, hybridization type and nature of bonding have been obtained by natural bond orbital analysis. TD-DFT calculations have been performed to recognize the electronic structure and to explain the related experimental findings. The CORMs have been screened for their antibacterial activity against Staphylococcus aureus and Escherichia coli in comparison to their parent drugs.