Quest of new molecular frameworks for photoinduced carbon monoxide-releasing molecules: a computational prospective

Manganese tricarbonyl complexes are considered as promising compounds as they release carbon monoxide (CO) upon irradiation of light. Carbon monoxide-releasing molecules may supply a controlled amount of CO to the biological systems. Therefore, this research area is a hot topic in medicine, especially cancer treatment. The designing and analysis of carbon monoxide-releasing compounds can be done using various experimental and theoretical methods. We have performed density functional theory (DFT) calculations to identify and scrutinize such molecules to investigate the ability to release CO. In this report, we have taken Mn(I) tricarbonyl complexes that bear di(2-picolyl)amine unit with different kinds of electron-withdrawing nature ligands. We have used density functional theory (DFT) to optimize different complexes with the B3LYP/LANL2DZ basis set. DFT and time-dependent density functional theory (TD-DFT) calculations infer that the designed carbonyl complexes (2 to 8) will release CO efficiently. The calculated results also suggest the transfer of electron density from the electron-rich metal centers to pi molecular orbitals of the ligand via strong metal-to-ligand charge transfer (MLCT) in the visible/near-IR region. The strong MLCT results weaken the metal-CO back bonding and promote the speedy CO-release.