Light-mediated CO release from a tricarbonyl manganese(i) complex with a bidentate quinoxaline ligand

Reaction between 2-(pyridin-2-yl)quinoxaline (L) and [MnBr(CO)₅] afforded a dark-stable fac-[MnBr(CO)₃L] that releases CO upon exposure to visible light (468-525 nm). Different structural elucidation methods, including X-ray crystallography, were used to thoroughly characterize the structure of the organometallic compound. Prior to recording the profiles of dark-stability and photolysis in various organic solvents, the complex's solvatochromism features were examined experimentally and through quantum chemical calculations. As solutions become less polar, the lowest energy transition in DMSO, which is observed at 487 nm, is red-shifted, which could be explained by negative solvatochromism. Illuminating the pre-incubated solutions of the complex in organic solvents at 525 nm, with or without calf-thymus DNA, hen white egg lysozyme, or histidine, yields a two-step process perhaps associated with the sequential release of 3 CO molecules. In comparison, the principal factor influencing the CO release kinetics of the complex is the medium and the percentage of DMSO for example, with minimal interference from the biomolecules.